Never had AT&T but just got charged

Hello,

Has it been happening to anyone else, that has never ever been associated with AT&T, got charge a HUGE charge? I have no idea how this happened as i have never had AT&T, have not done or used my card anywhere new, but just got charged for $1,391.00. The charge said it was from "AT&T COR DF" 

Any reply is helpful. I'm not sure how this happened as i've been very careful the last couple of years.