Comcast keep charging for monthly modem fee $6. when i found out, i bought a $80 modem and replaced the old one?. (same brand and same model number)

When i try to activate the new modem online (i have to do this because that is the only web page that comcast allow me to go), i got nowhere/. (failed to activate message repeatedly) However, I can open the online chat function using the new modem:. Then I chatted with 2 different technicians for nearly 2 hours 5:22 to 7:18 pm using the new modem and could not resolve the issue (i?.e I could not browse any other website)/. I finally got connected online by calling comcast technician (of course another 7 minutes of wait and listen through their advertisement)
Comcast claim that they do not have record of the chat'. But I do'. I began taking screen shots one hour into the fruitless chat..

What a service!
Their customer guarantee is totally worthless! 2f5956b