The last time I had something similar but about my broadband I phoned BT to check it out - it was a scam so I am always very wary indeed. Especially as a few months before I had been stung for £150. I got lucky and my bank (M&S) sorted it out and refunded the money. My problems were with cold callers on the phone. I now do not do any business over the phone and indeed I don't even answer their calls. It's interesting that each time the answerphone comes on the call ends.