Customers and business owners talked to by the Otago Daily Times about 12.30pm said the Milton ANZ ATM had been down since Monday afternoon, and the Westpac teller for "at least 24 hours".
Neither bank operates a staffed branch in the town of 2000, leaving the ATMs the sole banking facilities for customers.
Milton Post Centre owner and ANZ customer Anne Pierce said she had seen a succession of frustrated customers attempting to withdraw cash from the ANZ machine opposite her business since Monday afternoon.
She estimated between 15 and 20 people visited the ATM every hour - many returning repeatedly.
Although she was "resigned" to the situation, she said others were clearly angered by the apparent delay in fixing the problem, and a "lack of communication" from ANZ.
"We use it to do all our banking now there's no branch, so it's a bit annoying. But all they really need to do as a courtesy is put a sign up saying `out of order', and people won't keep trying to put their card in with no results. I'm not surprised people are frustrated."
Kiwibank customer Ross Finch said he was annoyed after checking both ATMs for the second time yesterday.
Mr Finch, a shearer, said many rural and small town residents relied on cash for everyday business.
"Some need it for trading, some for budgeting, and some just prefer cash. You know where you stand with cash and don't get any nasty surprises."
The situation could be a "Catch-22" for some people.
"What if you need money for gas, but then need to drive to Balclutha to get cash out? You're stuffed."
He said the prospect of a "cashless economy" - as predicted by some economic forecasters - was disappointing.
"There's a whole generation who don't use the internet and like the familiarity of cash transactions. I suppose we'll get by, but I can't say I'm looking forward to it."
Mr Finch had not been aware Milton had a third, private, ATM, in the town's White Horse Inn.
Pub staff said despite a $2.50 transaction fee, the machine had "taken a hammering" on Wednesday, but remained online throughout the week.
An ANZ spokeswoman said its Milton ATM had suffered a "touch screen issue".
A technician was working on the fault yesterday afternoon.
The bank apologised, and said the issue would be resolved "as soon as possible".
Westpac's ATM was restored to action at 1.15pm yesterday.
