Went to order a patio set from M&S online this morning, but two Mastercards would not go through, the lady said it was odd as they were not declined. Used my debit card and that was fine. Seconds later, the house phone rang with a recorded message (my husband answered) asking if his date of birth was a)1948, b)1945 or c)1949. He put the phone down. When we rang the bank, they said that both cards were fine, and they had not, and would never call and ask dob. We have now had another one asking us to call a number beginning 0800.
Google the number and see if other people have had that call. If so then I would inform your bank of the number and ask them to replace both cards just for safety.
Turns out it was NatWest! We paid the credit card off, then last month booked a holiday on it, plus a frock from M & S. they said it looked suspicious activity so blocked it! At least it is sorted out, but they said we did the right thing in cutting off the call when we were suspicious.
Be careful, though, as a while back I discovered that some scammers were using the NatWest number on the back of the card. Apparently they have technology to disguise a number with another one, or something.
So when you do a number check and you think it's ok, it really is NatWest, it isn't!
Anyway, the NatWest fraud department were aware of it, but took a note of my experience, which luckily did not involve any money.