AT&T 50% Off

A AT&T representative called me today that I am qualified for 50% off of my AT&T DirecTv services. I was told to get an Ebay debit card to pay one time $480.00 to AT&T and the rest of my bill for 18 months will be 50% off. I did  a research and find out that a lot of people have the same phone call for the 50 % off. I found out that this is a scam. My question is how did these people obtained my personal records (phone number, AT&T customer, etc...)? Please beware of this kind of scam.