In a bid to make the billing process more transparent, Eon will change the way it bills its customers from 19 April onwards.

The energy supplier said in a statement the removal of various discounts, (which it said will see existing customers on its standard variable tariff (SVT) pay on average around £22 more a year), will make its tariffs more understandable and easier to compare with those of its competitors.

But price comparison service Energy Helpline said the move could mean a rise of up to £50 annually for some Eon customers.

An Eon spokeswoman said the firm had “made no changes” to the prices it was charging for electricity and gas units.

She said the increase in customers’ bills was due to the removal of some of the discounts currently offered to customers for paperless billing and using both electricity and gas, and added: “We believe this will make it simpler and easier for customers to understand our tariffs and compare them with other suppliers in the market, the majority of whom do not offer these discounts.”

The company has also increased its standard charge for customers who choose to pay their bills by cash or cheque, to £10 per fuel per year. It said the majority of its customers, (almost three quarters), pay their bills by direct debit.

The spokeswoman said: “The impact on our customers’ bills will vary depending on payment method, bill choice and fuel selection.”

New legislation to allow energy regulator Ofgem to limit how much companies can charge customers for their SVTs is expected to come into effect next winter.

This will cap the cost of firms’ SVTs until 2020, and will be reviewed every six months, with extra safeguards included for customers on green default tariffs.