Savers have accused banks and building societies of denying them the best fixed-rate deals because of spurious delays when their previous deals mature.

Billions of pounds are tied up in fixed-rate savings accounts that were offering rates as high as 7% a year ago and are now maturing.

Sunday Times Money has been inundated with letters from readers incensed by delays in releasing funds, potentially costing them thousands of pounds in interest because they can not transfer to another top deal.

Richard Mason, a 45-year-old private-equity firm director from London, is angry that Bank of Ireland, which runs Post Office products, insisted on a five-day “validation” period when he wanted to transfer £1.06m from his Post Office growth bond to his HSBC current account. This was on top of the three days for the transfer — a process that could take one working day. Alternatively, Bank of Ireland would send a cheque — but this would take up to 10 days.

In the event, the transfer process took 20 days because of a series of administrative errors. Mason claims this cost him more than £2,500 in lost interest because he was unable to take out a different fixed deal.

“The net effect was that my £1.06m was sitting at Bank of Ireland earning 0.5% for 20 days when it could have been making 5%. It really is pathetic,” he said. Another reader, Gillian Francis, had to wait 17 days for the £150,000 she invested in a one-year fixed-rate account with the Post Office due to confusion over her address.

Bank of Ireland said: “The security mechanisms in place for withdrawals are well established and proven in Bank of Ireland, and are commonplace in banks all over the world. These controls offer high levels of protection for our customers’ funds and are an excellent deterrent to fraudsters.”

Several big high street banks, including Barclays, Halifax, Alliance & Leicester and Lloyds, allow customers to transfer matured bonds electronically only if they are moving to another in-house account. If the customer wants to move the money to a rival, they will be sent a cheque. Others such as HSBC and Chelsea building society allow electronic transfers out.

The UK Payments Association, which monitors financial transactions in Britain, said: “There is no practical reason why a bank should not be able to transfer money to another provider electronically.”

In May 2008, a faster payments service was introduced to reduce payment times from three working days to near real time. However, it did not cover the transfer of maturing fixed-rate deals.

Dan Moore at Which?, the consumer group, said: “Some banks still insist on using a very antiquated system when customers want to move their money out of a bank. Any delay in transferring money is a benefit to the bank that holds the money.”

Laurence Flint, 61, a computer programmer from Brondesbury, north London, fears he will miss the chance to take out a National Savings & Investments Guaranteed Growth bond, which pays a fixed 3.95% for one year, because he is unable to move £100,000 out of his Abbey Flexible Saver account, currently paying 0.1%.

Abbey claims it cannot transfer such a large sum because of a fraud risk. Instead, it asked Flint, who is disabled, to come to a branch. “The reason I opened the account, which was phone-based, was so I didn’t have to travel to the branch,” he said.

Flint tried to transfer just £25,000 but was told the fraud team were unavailable to approve that transfer, too.

Abbey said: “Mr Flint was unable to transfer his funds via the telephone as one of our safeguards against potentially fraudulent activity was triggered. This is in place to protect the customer. We recognise that this caused some inconvenience to Mr Flint, for which we apologise.”

Readers have also complained about Bradford & Bingley, Birmingham Midshires and Barclays.

Andrew Hagger of Moneynet, the adviser, said: “Every day a savings provider has your lump sum without having to pay you the going rate is a bonus for them.”

TRANSFERRING FROM YOUR FIXED-RATE DEAL

Your questions answered:

Will my provider inform me about my bond maturing?

Most will inform you two to six weeks before maturity, although there is no requirement for them to do so.

Michelle Slade of Moneyfacts said: “Others may advise savers at account opening, putting the onus on the customer to remember the maturity date and to move funds if required.”

How can I receive my money?

Most providers offer either a cheque or electronic transfer, either by Bacs, taking three to four working days, or Chaps, a one-day transfer with a fee.

What if there is a delay in receiving my money?

If you feel your bank is delaying the transfer, or it owes you lost interest, first complain to the bank itself. The bank has eight weeks to resolve your complaint, after which, contact the Financial Ombudsman on 0300 123 9123.

What are the best deals now?

Skipton building society pays 5.35% on a five-year deal, though experts recommend a shorter term. The best three-year bond is from ICICI, which pays 4.7%, while NS&I is currently the top one-year deal, paying 3.95%.