First National Bank clients reported extra money in their accounts on Tuesday, and on Wednesday morning FNB confirmed it had made a mistake.

The bank now wants the money back – which is not going down well with customers.

It is not clear how much the bank paid out to customers in total, or whether the error was linked to a system update FNB did during the weekend.

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First National Bank on Wednesday morning confirmed the unlikely stories its clients started to share on Tuesday: free money in their accounts.

The bank said an error meant balances had been reflected incorrectly in some accounts.

The highest reported though unconfirmed amount to date is R3,600 but anecdotal evidence suggests a very large number of customers saw lesser amounts, of around a few hundred rand, mysteriously appear in various bank accounts.

Some questioned the windfall – and were told it was legitimate.

Second FNB banker i spoke to? pic.twitter.com/2RSd1O167z — Londiwe (@londs_s) June 18, 2019

Check your banking app. I legit woke up with just over R3600 MORE in my account ?? ?? — Mochabe???? (@Luda01) June 18, 2019

That did not last.

According to Daniel Kaan, FNB's transactional banking spokesperson, the incorrect balances in clients' bank accounts were due to delayed debit card transactions.

See also: FNB clients have won more than R800 million in the Lotto by playing via the bank

And now FNB wants their money back. According to Kaan, the bank has been in contact with affected customers and the matter "has been resolved" – though that does not appear to be entirely accurate, and the bank may find the situation more tricky than its statement suggests.

So FNB came back looking for their money and it wasn’t there. I’m closing this account tomorrow pic.twitter.com/bQnXn0RuQp — Mazwi Blose (@MazwiBlose) June 18, 2019

So FNB is trying to reverse the money they paid to my account... My Account: pic.twitter.com/2j6YWAaYli — Collen (@KCollenm1) June 18, 2019

Others were not sure whether to spend the money, if at all....

Should I move the amount fnb gave me? If I use it will I get into trouble? — Siyanda Dzenga (@SiyaBunny) June 18, 2019

But some piled right in.

I've already finished it. Andingeni ndawo if it was a malfunction in their system ?? — Aluve (@aluve_ngoo) June 18, 2019

It is not yet clear how much the bank gave away in total as FNB would not provide further information on questions from Business Insider South Africa.

FNB did not say whether the errors were linked to a system update it conducted over the long weekend.

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