How to throw the right gas switch

'Because we are a not-for-profit company, our focus is on getting the lowest prices to customers rather than giving commission to the energy comparison services,' says Ebico managing director Phil Levermore. 'But the commercial pressures on these companies, who present themselves as a neutral voice in the market, mean they prefer that customers switch to suppliers who pay them a fee.'

Britain's biggest switching site, uswitch, does list Ebico's tariffs but only if you ask it specifically to list 'social tariffs' as well as 'all tariffs' - not just the ones uswitch has a commercial arrangement with. When we opted into 'social tariffs' on uswitch, Powergen's Age Concern tariff did show the greatest saving at £68.51 - more than twice as much as we would have saved with the standard tariffs it recommended. This was followed by Ebico, which uswitch estimated would save us £62.68, again twice as much as its previous top listing, Atlantic.

'We ask people to opt in because the social tariffs are targeted at specific social groups and the majority of providers on our site would rather their products were targeted at the right kind of customer,' said Tim Wolfenden, senior product manager of home services at uswitch.

When asked why the uswitch results did not list British Gas in its top five, as two of the other sites did, Wolfenden said that, although the site should have listed the energy giant among the results, uswitch does not have a commercial relationship with British Gas, which means you cannot switch to it through the site.

Simply Switch says it does usually list Ebico's tariffs, but that the tariff details have been temporarily taken off the site while they are being updated. However, Karen Darby at Simply Switch added: 'Ebico's is a social tariff not designed for people who are wealthy and who pay on direct debit.'

But Ebico's Levermore says: 'We are absolutely delighted to take people on direct debit. In fact, we charge everybody at the same rate irrespective of the form of payment they choose, so we need a good mix of customers.'

While the switching sites undoubtedly offer a valuable service to those wanting to save money, not all experiences with switching have gone smoothly. Cash reader Virginia Willesden switched from British Gas to Utilita last April. Utilita has since ceased trading and all its customers have been transferred to EDF Energy.

'In October, Utilita wrote to us to say it was increasing our monthly direct debit from £130 to £149.50. We thought we'd let it go because we didn't want to switch again,' said Willesden. 'A month later we got a letter from EDF saying it had taken over Utilita's customers and then, at the end of January, we had a final bill from Utilita telling us they had added a surcharge of £40 to our bill and that we were in credit by almost £300.'

Utilita has a message on its phone line which states: 'All of our customers who are in credit with us will have their money credited to them within 14 days of final settlement.' However, Willesden says the 14 days are now up. 'We are now faced with the prospect of losing £300 - something which had never entered our heads when we switched. I thought we were being sensible.'

Customers who switched to another small company, Zest4, are in a similar situation. It went into administration last year and Energywatch says that, while it is in talks with the company's administrator, customers are very unlikely to get back any money owed. However, the watchdog says this should not necessarily be taken as a warning to steer clear of all smaller companies.

'This could happen with any size company. What I would say is look carefully at the company before you sign up and keep on top of your bills so that what you are paying is all that the company is owed and not more,' says Kerr. 'If you're paying by direct debit you need to keep an eye on your meter readings and get regular statements so you can get on top of any under or overpayment quickly.'

Cut your bills

Look for an Energywatch accredited website. This means it will comply with the watchdog's code of practice · Compare results across a number of such sites. Make sure that you check any box that asks if you want to see all the tariffs.

Online tariffs are often cheaper than those that send you paper bills. Most switching services include these, but not all will sign you up through their service.

Paying by direct debit generally works out cheaper, but take regular readings and check these against your bills.

A fixed or capped product might help. You pay a premium to ensure your monthly bills stay the same in the case of a fixed rate product or do not rise above a certain level in the case of a capped tariff - but you are paying for certainty.

· The Observer has a commercial relationship with Simply Switch