A number of holidaymakers who have booked with major online travel agent Alpharooms have reported turning up to hotels booked through the site only to be forced to pay again or seek alternative accommodation because their rooms hadn't been paid for.

Alpharooms says around 50 customers' hotel bookings were "mistakenly cancelled" due to a "technical issue". It has apologised and says it's now contacting those affected.

Several travellers contacted MoneySavingExpert.com founder Martin Lewis over the weekend, while others complained to Alpharooms directly, with one tweeting: "This has just happened to us – hotel demanding 700 euros."

One MoneySaver emailed us today to say his wife had experienced a similar issue this morning while checking in at an apartment in Nerja, Spain.

Another customer sent us a picture of a letter he'd been given by his accommodation, Benal Beach Apartments in Andalucia, Spain, stating Alpharooms customers must pay for their stay again. The Benal Beach resort this morning confirmed to MoneySavingExpert that it had asked all Alpharooms customers arriving over the weekend to pay for their rooms again on check-in.

Alpharooms, which says it has more than a million customers a year, has posted the following statement on Twitter: "Owing to a technical issue on Friday 14 October some of our customers' bookings were mistakenly cancelled.

"We are in the process of contacting all affected customers and would like to apologise for any disruption caused."

A company spokesman told MSE the problem was due to a technical failure by its payment provider, which led to some hotels and resorts cancelling customers' bookings.

He said the majority of affected bookings were for check-in dates over the last weekend, but a small number of bookings have also been affected this week.

What are customers saying?

We've seen a number of complaints on social media since Friday, including several from holidaymakers visiting Spain and one from someone on a trip to Prague.

In a series of near-identical replies to affected customers, Alpharooms has urged them to "contact our emergency team via the number on your voucher".

What are my rights?

Alpharooms is now contacting affected customers and says it will refund those who were forced to pay twice, but it didn't yet have any details of how these refunds would be handled.

A spokesperson said the firm wasn't currently planning to offer compensation to those affected.

If you've been hit by this issue please email us and tell us your story.