'I put the wrong date when getting a comparison quote... and my EXISTING insurer hiked my premium'

'My premium increased by almost £50 – I'm a bit gobsmacked'

Mary, who lives in Cumbria, contacted us after Admiral increased her premium by £47. She'd guesstimated the date of an old speeding fine as 2014 rather than 2013, when using Compare The Market to check how competitive her renewal was.

Mary told us: "I did have a speeding fine, but I just couldn't be bothered to find the details so I guessed 2014 – it asked if I had a speeding fine in the past five years so I just put a rough date in."

In the end, Mary didn't click through from Compare The Market's results page – she decided to haggle with Admiral instead and agreed a lower renewal price. So she was shocked when Admiral took an extra £47 from her account a few weeks after she renewed.

When she queried it, Admiral told Mary her premium had gone up because it had been told she had an extra driving offence on her record. Admiral says it wrote to Mary to confirm the change to her driving record, but Mary says she never received the letter.

Mary said: "I had to prove I didn't have any points on my licence, as they have now expired... I'm a bit gobsmacked."

What does Admiral say?

An Admiral spokesperson said: "When a customer completes a quote via a price comparison site, that site will pass on the quote details to all the insurers on its panel in order for them to return a price.

"As her existing insurer, we had details of Ms Moscrop's motoring conviction from May 2013. However in this instance she entered another date for a motoring conviction, guesstimating a date in April 2014. We thought this was a new, additional conviction and it would have fallen within the disclosable period – ie, it would have been relevant to the premium for the current policy and would therefore need to be taken into account.

"This does highlight the need for customers to be accurate in the details they provide when getting a quote, whether that is direct or through a price comparison site."

Admiral says it appreciates mistakes can be made by customers and so writes to them to confirm the new details, and gives them two weeks to respond before making changes to the premium. Though in this case, Mary says she doesn't recall receiving a letter.

Admiral has now refunded Mary the extra £47.

When do comparison sites share info with insurers?

To find out how common this problem could be, we asked the big four comparison sites what their policy is on sharing info from quotes.

Compare The Market, Confused.com, Gocompare and MoneySupermarket all told us they pass on quote details to every insurer featured on their site for that particular type of insurance in order to obtain accurate quotes. However they have different rules on what insurers can do with that info.

• Gocompare told us quote details can't be used to update policies mid-term. It says "using customer data to make mid-term adjustments to an existing insurance policy is not a permitted use of the information we share with our panel".

• Compare The Market, Confused.com and MoneySupermarket say it's up to insurers whether they use quote details to update existing customers' policies. Compare The Market head of motor insurance Dan Hutson said: "When visiting a price comparison website to obtain an insurance quote, it's vital that all questions are answered honestly, taking care that the information disclosed throughout the quote is accurate and complete to the best of your knowledge. If customers don't do this, an insurance provider could increase a premium, cancel a policy, treat it as if it never existed, refuse a claim, or not pay the claim in full.

  "All insurance providers have their own data privacy policies... but essentially, they are able to use quote data they receive from price comparison sites for the purposes of providing a quotation, analysis and fraud."

  Confused.com says it shares quote details "for the sole purpose of retrieving tailored prices, in line with our privacy policy". But it added: "If one of our panel is the existing insurer and they have reason to believe their existing customer's circumstances have changed they may make efforts to verify it. This should be outlined within the insurer’s privacy agreement with the customer."

  A MoneySupermarket spokesperson said insurers using its data would have to comply with their own privacy and data policies, and added: "If the insurer believes that the new information makes the policyholder a different risk from what they had been told, then the insurer may contact the policyholder for that purpose. That is a decision for the insurer."

How do insurers use the info they get from comparison sites?

We asked seven major insurers whether they would use comparison site info to update existing customers' policies in the same way as Admiral:

• One insurer – Co-op Insurance – said in some cases comparison site info could affect an existing customer's policy. A Co-op spokesperson said: "If we are made aware of any differences in the information, we would determine if this was a genuine mistake and whether the new details would make us reconsider the premium originally quoted. 

  "On occasion we may need to investigate whether there was any fraudulent intent and this may lead to additional actions such as cancelling the policy. This is standard industry practice and we would not automatically take these measures until we had completed those investigations."

• Two insurers – Churchill and Endsleigh – declined to comment. Neither would tell us what their policy was.

• Four insurers – Axa, M&S Bank, Tesco Bank and Zurich – said they wouldn't use comparison site info to update existing customers' policies. Axa wouldn't give details, but said it wouldn't use data in this way. M&S Bank told us: "We don't currently use information submitted to price comparison sites at quote stage to make changes to existing policies", while Tesco said: "We quote on the information that is directly disclosed to us and would not make adjustments to policies based on information supplied by the aggregators. We have robust pre and post-sale validation processes in place and should we find any discrepancy in the details provided, we will always contact the customer to ensure we have the correct information." Zurich said: "We will not use [comparison site quote info] to update our existing customers' information".

ALWAYS give comparison sites the correct info

Comparison sites are a great way of quickly comparing prices for almost all insurers, and so can be a great tool to check if you're getting the best price.

But Mary's story shows the importance of making sure you always enter the correct details whenever you do use them, as the data could well be fed back to your existing insurer and any discrepancies could cause problems down the line even if you don't end up purchasing a policy.

If you do click through to an insurer from a comparison site, always make sure any details have been copied over correctly.

And remember, not all insurers are featured on comparison sites. See our Cheap Car Insurance guide for full help on how to find the best deal.