I had a very similar thing happen to me, one of the local Barclays cashpoints was stalking me and ringing us at all hours of the day and night, repeatedly. We had to unplug the phone for 4 days. It took ages to get it sorted but BT malicious calls people were very helpful, and the Barclays people were too, even if they obviously thought I was mad when I first called.
yes! though you normally pay a fee to transfer your balance onto it. Also its not for spending as its 0% for balance transfers not 0% for spending. If you get one of these cards NEVER spend on it. Have a looky through Martin Lewis' Money saving expert site for good advice and info