The exact same thing happened to me and I had my current a/c emptied along with my overdraft. Nobody knows my password or info relating to my a/c.
It seems I bought a TV in Southend, a HiFi in Windsor and made no end of cashback withdrawls in the midlands at various supermarkets .. all on the same afternoon. The bank had picked it up and made me aware. The strange thing was that they let whoever it was carry on and completely empty my a/c., instead of shutting it down. They went on to pay gas bills, electric bills and to top it all, they paid someones tax bill .. straight to HMRC.
The Police love names and addreses when they are after fraudsters.
It took five days to get all the money back in my a/c and I only had to sign a disclaimer saying that I knew nothing about any of these transactions.
Got a feeling my bankcard was cloned somehow ?