Although, utility companies have the unpleasant habit, possibly protected by some clause in the small print (and probably unenforceable as 'an unfair contract term') whereby they treat a double payment as credit against your next bill. The absurdity of this is simply seen. Suppose someone with a bill of £40,000 to pay wrote the cheque out with others, one of which was for the utility, and absent mindedly put the utility as the payee rather than HMRC or the solicitor conveying their new house to them. What would the utility company say then? And how long do you think they would stay out of the courts ?