When called by Susanne I asked to be taken off their list, even used please in my request. I was told no and hung up on. When I called back the number I got the recording that the number had been disconnected. How can that be in 15 seconds?
They intentionally gave you a false number. It's called spoofing. Last thing they want is junk calls coming in from people who want off their list. Surprised at their honesty in refusing to remove your number. These types usually just lie about that.
Now that they know your phone gets answered, expect the calls to continue if not increase.
Moral of the story: If you don't know the caller, don't engage. Don't pick up, don't talk, don't ask to be removed. Like feeding a stray animal, it just guarantees they come back.