Smaller energy suppliers are continuing to outperform the big six when it comes to customer service, a new poll of MoneySavingExpert.com users reveals, despite those at the bottom of the table significantly upping their game in the past six months.

Gas-only supplier Zog Energy has been ranked best for customer service for the third time running, while Ovo Energy, in second place, maintains its long-standing position at the top of our rankings.

Flow Energy, First Utility and British Gas-run Sainsbury's Energy round out the rest of the top five, with many of the larger firms apparently struggling to provide their massive customer bases with great customer service.

Yet while Npower and Scottish Power again languish at the bottom of the pile, both have made significant gains, with the proportion of customers ranking each 'great' improving since last November by 15 percentage points and 14 percentage points respectively. And Co-op Energy, though third from last in the latest poll, has seen the proportion of users rating it 'great' leap from 21% to 48%.

MoneySavingExpert.com carries out its energy firm customer service poll twice a year, and ranks all providers attracting at least 100 votes from users. Almost 5,000 users took part in our March 2017 poll.

To help you pick a firm with proven customer service, you can now do a full comparison via our Cheap Energy Club and filter your results to only show those with a certain rating, based on our service polls.

Martin Lewis
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The results in full

Here is the full table of results from our latest energy company service poll:

Energy company service rating, March 2017
(Results and ranking from November 2016 in brackets)
Rank Provider Great OK Poor
1 (1) Zog Energy 96% (90%) 4% (1%) 0% (9%)
2 (2) Ovo Energy 89% (86%) 8% (8%) 3% (6%)
3 (4) Flow Energy 75% (77%) 17% (16%) 9% (7%)
4 (8) First Utility 70% (60%) 18% (21%) 11% (19%)
5 (5) Sainsbury's Energy 67% (69%) 23% (25%) 10% (6%)
6 (6) EDF 64% (60%) 26% (29%) 10% (12%)
7 (11) GB Energy (a) 64% (46%) 19% (18%) 17% (36%)
8 (9) SSE (b) 57% (56%) 26% (25%) 17% (19%)
9 (7) E.on 53% (60%) 32% (27%) 15% (13%)
10 (10) British Gas 53% (47%) 26% (28%) 21% (26%)
11 (14) Co-op Energy 48% (21%) 26% (22%) 26% (56%)
12 (12) Scottish Power 47% (33%) 22% (23%) 31% (44%)
13 (13) Npower 37% (22%) 28% (26%) 35% (52%)
Order calculated by 0 points for poor, 1 for OK and 2 for great. 4,863 votes in total – we've ignored providers with fewer than 100 votes. The percentages may not add up to 100% due to rounding. (a) Now part of Co-operative Energy. (b) Includes Atlantic, Scottish Hydro, Southern Electric and Swalec.

What the energy firms say

A spokesperson from Npower says: "We’re pleased to see the improvement in our scores as we have been working very hard at making our customer service better. We also recognise that despite reducing our complaint volumes by 50% last year, there is much left for us to work on."

A spokesperson from Scottish Power says: "We are delivering a range of improvements to the services that we offer our customers. Overall we have seen a significant reduction in complaints during the first three months of the year, as well as recently launching a new simplified bill design. We will work hard to continue making further improvements."