Worried customers claim they have been unable to move their current accounts after their building society announced plans to close them.

Norwich and Peterborough Building Society, which is owned by Yorkshire Building Society Group, on Wednesday unveiled proposals to close 28 branches across Norfolk, Suffolk and Cambridgeshire, with the potential loss of 136 jobs.

However, customers hoping to move their accounts using the seven-day switch service, introduced following a recommendation from the Independent Commission on Banking, have been told they are unable to do so - because it is not signed up to the scheme.

In an open letter to the building society, Peter Williamson, a loyal customer who has banked with the Norwich and Peterborough for more than 13 years, said: “I have tried to change to the Co-op bank but I cannot use the switch system – organising existing direct debits, etc – because the N&P is not part of that system.

“I wish to complain about this because not only are the N&P and YBS rejecting long-standing customers out of hand, they are also making it as difficult as possible for us to deal efficiently with the enforced change.”

The Yorkshire aims to close 20 Yorkshire Building Society branches in May and 28 N&P branches from September this year, with the N&P brand disappearing by April 2018, and will contact customers directly to explain the changes to their accounts.

It said it was no longer “cost effective” to keep the branches open, with only 23 per cent of its customers having used a branch in 2016.

A spokesperson for the Norwich and Peterborough Building Society said: “It’s correct that we’re not part of the seven-day switching process, but this shouldn’t affect customers who want to switch.

“We’ll do all we can to support and make the changes as smooth as possible for customers should the proposals go ahead.

“However, it’s important to remember these are just proposals at this stage. Customers should receive letters over the next two weeks outlining all the proposals and what they might mean.”

So what happens next? Assuming the proposals go ahead, the bank says…

• We will write to customers to provide details of how they can switch or close their account, along with information specific to their personal circumstances.

• We will direct customers to the Money Advice Service for impartial advice about current accounts

• Once a customer has chosen a new provider they would need to provide them with their N&P current account details.

• When the new provider contacts us we would provide them with details of any regular payments so these can be set up on the new account.

• We would then arrange to transfer any account balance to the new account, and then close the N&P account when the customer or new provider asks us to do so.

• For personal accounts, all benefits such as free card usage abroad, VISA debit card and cheque payments, Sentinel Gold cover, overdraft and fee free buffer, will continue until the account is closed.

• Customers will be asked to close their account before August 31, 2017.

Norwich and Peterborough branches to close:

• Aylsham Road, Norwich

• North Street, Bourne

• Bowthorpe Main Centre, Wendene, Norwich

• Bretton Centre, Bretton, Peterborough

• Market Place, Bungay

• St Andrews Street, Cambridge

• St Stephens Arcade, Chapelfield, Norwich

• High Street, Dereham

• Wales Court, Downham Market

• Bridge Street, Fakenham

• High Street, Huntingdon

• High Street, Leiston

• Broad Street, March

• Market Place, Market Deeping

• Market Place, North Walsham

• Market Place, Oundle

• Plumstead Road, Norwich

• High Street, Sawston

• High Street, Sheringham

• Market Place, Southwold

• Sheep Market, Spalding

• High Street, Stamford

• King Street, Thetford

• High Street, Watton

• Skaters Way, Werrington, Peterborough

• Market Place, Whittlesey

• Station Road, Wroxham

• Market Place, Wymondham