Men Impersonating Comcast Technicians

I talked with a person named Peter who said he was fixing my internet, said he was also going to have my router upgraded and a bunch of other stuff.  After 8 or 9 days he said he'd transfer me to a Technician who would be crediting my checking account because my service wasn't working correctly.  This Technician said he made a mistake putting money in my chcking account  and that I owed him the difference $2500.  And eventully he started to insist I purchse several gift cards and give him the numbers on these.  Luckily I did not.  But my email still is not working.  During this time I supposdly had an appointment during which a Comcast rep would replace my router.  A person came and did that but now I don't know if he was really from Comcast.  I had to shut down my checking  accoiunt and wonder what these imposters will do next.  I want to speak with a REAL COMCAST REPRESENTATIVE about this problem that has created so much trouble for me.  If someone doesn't contact me today I will shut down everthing I have that is in any way connected with COMCAST.  I do not know how to get through to Comcast or how they will get in touce with me but that is what has to happen next!