Long time ago...back in 1990: we moved across the county to shorten wife's commute. We didn't drag our phone number with us -- the phone company wanted a lot of money for that privilege back then. They gave us a very nice phone number. I think it was 965-0333. Or something like that.

Well, we started getting calls for Budget Rent-a-Car. You see, they used to have a suburban branch near us, but it closed 6 months before, and when we applied for a phone line, the phone company recycled that number to us.

We were technologically savvy -- we had an actual answering machine. With tiny cassette tapes. We changed the message to state "this is not Budget Rent-a-Car. This is a private residence. Please leave a message for 965-0333." Even with that message, one day I came home from work to a message (old-lady voice): "Hello? I'd like to rent a car?"

My point is it is very likely that you are the "illicit" user -- that the person who's drug store account you've stolen legitimately had what's now your phone number back when they set up the account. I'm not aware of anything mandating that they change their drug store rewards account just because they've given up a phone number.