805-372-0050 Threatening ATT Discontinue Service Scam Calls

Receiving numerous calls threatening to discontinue my AT&T services. I do not have AT&T but they insist that my internet connection with Comcast is used by AT&T and that my computer has been hacked and used criminally. They offer to get rid of the scammers by going to my computer and turning it on for their direction. I asked them for their number and they gave 805-372-0050 but the caller ID names their number as 804-209-2576. If you call the 805 number it goes to AT &T and it sounds like the persons who called in a foreign accent, but the 804 callback says this number is not in service.