If you went to the cash machine....

[bonj2]

keyed in £30 and £200 came out, then did it again and another £200 came out what would you do???

there's no point saying "what if", because that would never happen.
If it was possible for it to happen, it would be happening all over the place and banks would go bankrupt and the value of the pound would be degraded.
There's double and triple checks and quadruple checks - in software, hardware, and mechanical methods.

 

[Bigtallfatbloke]

Tell the bank it wasnt you taking the money out and that you have been the victim of card fraud.

 

[Aint Skeered]

I thought I got lucky back in the late 70's when the local petrol stations self service machine ( pound note in the tray type thingy) went wrong and was dishing out unlimited free petrol. word spread round, and people where turning up filling the cars petrol cans and anything else they could lay there hands on.
I turned up and after queing for about 10 mins, arrived at the pump, just about to fill the car, when the village copper turned up

 

[cisamcgu]

Take the money, walk into the bank, and explain what had happened, and wait until they show you if the money has come from your account or not. If it has, then keep it, if it hasn't, give it back - but get proof from them, about what happened, and a reciept for the money.

You cannot keep the money, if it is not yours, that is stealing !

Andrew