Who do you bank with??? This has happened to me a few times. The first time it happened I contacted my bank and they assured me that I would not be charged. however, My customers bank may charge her for having insufficent funds. By the way Ihave a business account. Not sure if that makes a difference.
Alliance & Leicester (business account).
If they try and charge me for my customer's bad ways in the future, then I'll be changing my account. I've just joined the FSB (Federation of Small Businesses) and they promote the Co-operative bank (free banking). I need to investigate this further.