Elena Harrow keeps two sets of energy correspondence on the kitchen table: letters from the supplier she left when it failed, and messages from the company that received her account. She is not certain which document gives the balance she should now be working from.

Harrow was a Clearwell Energy customer before its October failure and the transfer to Brightmere. She says she has tried to obtain an explanation of the readings used to establish her account. 'I am not saying a particular figure must be wrong,' she said. 'I am saying I cannot follow how the old information joins the new bill.'

A former Pennant Power customer, Bernard Keldon, describes a different question. He wants confirmation that information he supplied about his account has been received. He says he has found it difficult to get through to someone who can tell him whether the next message replaces an earlier one or concerns a separate part of the transfer.

'When you are told to keep the paperwork, you do,' he said. 'Then you have all this paperwork and you still do not know which question to ask first.' Both customers are seeking explanations of how their own records have been used in the transfer.

Brightmere took on about 108,000 Clearwell customers after its failure in October and about 72,000 Pennant customers in December under Ofgem's supplier-of-last-resort arrangements. The supplier has opened a major recruitment campaign at Filton to strengthen customer-service capacity as the transferred accounts are established.

A company spokesperson said transferred records did not always arrive in a form that allowed every question to be answered immediately. Information had to be checked before Brightmere could provide a reliable account explanation. The spokesperson said the company understood that receiving correspondence from a new supplier could be confusing and encouraged customers to keep readings and previous statements available.

Independent consumer adviser Asha Dorsley said an unresolved question and a confirmed error should be distinguished when seeking help. A customer might need an explanation of how a figure was calculated, or might have documents showing that information had been recorded incorrectly. Those situations could require different checks, she said.

'If the reply does not address the question you actually asked, keep the question clear when you write again,' she said. 'You should not have to decide whether the problem belongs to billing, migration or another department before anyone can understand it.' She said a supplier's response needed to tell the household what was being checked rather than merely repeat that a transfer was in progress.

Brightmere said it was working through the information and would respond to customers whose accounts required individual review. Harrow said she would welcome a message that separated the part of her bill already confirmed from the part still under investigation. Keldon is looking for something more basic: an acknowledgement that the question he sent is the one the company is answering.