A computer problem which left up to 3.3 million Post Office account holders unable to access their savings through pin pad machines has now been resolved, the company said.
Transactions involving Post Office card accounts, and debit and credit cards using pin pads at branch counters were all affected by the technical glitch, but normal service resumed at around 3.30pm today, a spokeswoman said.
Post Office commercial director Martin Moran said: "We apologise to customers for any inconvenience caused by a problem with the pin pad system in our branches.
"Normal service was restored this afternoon, including for the Post Office card account, and credit and debit card cash withdrawals."
Special arrangements had been put in place to ensure emergency cash payments could be made to pensioners and benefit claimants unable to otherwise get any money out.
All 11,820 branches remained open with customers still able to withdraw cash from any of the Post Office's 2,000 ATMs, which were unaffected by the problem.
The spokeswoman added that Wednesday is usually the quietest day of the week for Post Office transactions.