You know, I had the same problem last year.... I don't think I tried to buy anything online, but for some reason I had to call the bank to chase something (oh, that was it - the chip had died in my debit card and I needed a new one) and they were *absolutely* insistent that the three-digit code on the back of the card was wrong, and I had to go into my bank in person to sort it all out. I do believe there was much yelling on my part until the whole thing got sorted out - being told that "oh, we'll have a new card sent to you in 10 days" isn't much good when you have no way of paying for anything in the meantime!

I hope you have much better luck with your bank - just stay away from Abbey, seriously... >_<