Money Transfer

We were transferring money between banks. Receiving bank said we'd got a couple of numbers wrong and they were voiding the transaction- so we sent the money again.

However what they said they were doing wasn't what they'd actually done. They hadn't voided the first transaction but let it go through- with the result that the account we were sending to received the money twice over. Luckily the recipient is someone we can trust- and they sent us the surplus back...

And if they hadn't been?

Then things could have become very complicated and fatiguing.