Thanks for all the advice, but......... it's a letter ! Sorry I didn't make that clear.
I do know that email is never to be answered, and phones should be treated with caution.
Gives me a date my card will be stopped, and new ones issued, freephone number to call, letter under Bank of America heading, through subsidiary company MBNA, Card services , Chester.
Shall call the 0800 number tomorrow, and report back.
I'm interested in asking why I get a possible danger alert, and then give a date beyond which I'll be safe, and also why they don't stop it NOW

But they do say if it gets mis-used I won't have to pay - nice to know, gives me a warm glow.
I must say, a positive blizzard of replies - just shows this is the place to pick up stuff like this.