Existing energy customers barred from cheapest deals
Four of the UK's largest energy companies have been barring their own customers from some of the best deals for gas and electricity, the BBC's Moneybox programme has learnt.
The cheapest deals are often reserved for new customers only.
Meanwhile existing customers have been offered deals which can be hundreds of pounds a year more expensive.
The four companies, E.ON, EDF, SSE and British Gas said they were simply responding to changes in the market.
While the British Gas tariff has now been withdrawn, other suppliers are still restricting their offers to new customers only.
Such deals were originally banned by the regulator Ofgem in April 2014. Following a recommendation from the Competition and Markets Authority (CMA) in April this year, Ofgem let it be known it would no longer enforce these rules.
The discovery of such deals has as come a surprise to some leading industry figures.
Ken Geddes is the chief executive of Scottish-based Energylinx, the fourth biggest energy price comparison business.
When the BBC told Mr Geddes about the new tariffs, he declared himself "stunned" by the difference between the prices some companies offered new and existing customers.
Mr Geddes immediately tested a new-customer-only tariff from E.ON, launched in mid-September.
He first applied as an E.ON customer and then as a customer of another company. The difference in the the two prices he got from E.ON was £260.
"Having spent over a decade doing this job, I don't think I've ever seen that differential", Mr Geddes told the BBC. "I'm just gob-smacked as to the difference in price".
Large differences in price between new and existing customers are not confined to E.ON.
In the summer, British Gas launched a new-customer-only one year tariff offered exclusively through Uswitch - the UK's biggest energy price comparison website.
For new customers with average household energy consumption, the British Gas "Home Energy Exclusive Jun 17" tariff cost £735 a year. But for existing customers - barred from that deal - the best British Gas price for the same amount of energy was £989.
That British Gas tariff has now been withdrawn but others are appearing.
The SSE new-customer-only tariff, launched in September, offered new customers on average consumption a year's energy for £759 . For existing customers, SSE's best deal cost £972 - a difference of over £200.
Customers were unlikely to have learned such low-priced tariffs were available from their companies even if they searched Uswitch and Energy Helpline.
That's because such websites start by asking users for the name of their existing energy supplier. New-customer-only deals from that supplier are then filtered out.
As a long-standing customer of EDF, I wanted to find out what tariff I would be offered.
In a web-chat, I was told the tariffs available to me were: "Blue+ Price Protection Sep 2017" - costing £133 more than EDF's new-customer-only tariff, and "Blue+ Price Freeze Sep 2018" costing almost £300 more.
Were these the "very best tariffs EDF offers?" I asked the agent.
"Yes" was the emphatic reply.
When pressed about the much cheaper new tariff EDF had just launched, the agent replied, "I'm very sorry. This is only for new customers - not existing customers".
On Friday, EDF relaunched their new-customer-only deal, cutting the price by around £50 a year. So it's a better deal than before but it's still not for existing customers.
Not all major energy suppliers plan to offer such tariffs.
Scottish Power's commercial director Colin McNeill told the BBC his company would not offer them.
"These tariffs must stop," Mr McNeill said. "We must recognise that we are still not a trusted industry, and perceived sharp practices do the industry no favours."
With Scottish Power, he added: "Any of our customers can switch freely to any of our tariffs at any time."
The four energy companies which have offered the new-customer only tariffs, E.ON, EDF, SSE and British Gas, all say that they are responding to changes in the energy market and that their new tariffs are part of a strategy to serve a wide range of customers.
All four companies declined the BBC's invitation to be interviewed about their new exclusive offers.
Ofgem's chief executive Dermot Nolan told the BBC that Ofgem had acted on the CMA's recommendation "to make energy competition more similar to telecoms because on the whole that will mean lower prices and better deals for consumers".