Once the transaction goes through (i.e. not preemptively blocked), you are at the mercy of the bank. Most of the time it works, but I have friends' stories of l

Once the transaction goes through (i.e. not preemptively blocked), you are at the mercy of the bank. Most of the time it works, but I have friends' stories of losing several thousand dollars on a chequing account due to fraud and being unable to convince their bank that they deserve their money back.