If you have two lines of prices on your bill for the period covering July, it may be because prices change on 1 July each year. Where the new prices happen part way through your billing cycle, we use pro rata to calculate your bill. You’ll be able to tell as the front page of your bill will have a message advising this.
For example if your billing period was from 20 April to 19 July, you will be charged the old prices up to 30 June, and the new prices from 1 July. On your next bill you’ll only have one line per tariff. We’re required to pro rata bills for price changes under the National Energy Customer Framework.