For your information unless your technology is compromised I would say they have your details via legit call centers. They pass information around.
I had a legit Three support call some time ago. I remember being told to take the offer from a future sales call. That call came, they wanted all sorts of information. I just politely said I can't have the offer because I can't provide the information. The call ended with a simple bye.
If you ever want to be amused search YouTube for scam callers. Some are truly hilarious. The rage
