comcast They screwed up my new modem and then started asking me money to diagnose the problem Nationwide

I was using Comcast services from last 9 month without any problem. 

Suddenly they started asking me to put new DOCSIS 3.0 modem, 

I purchased modem, and put it. For configuration they taken 2 hrs and things were all good. 

Today I reported them for slow internet speed, and their level 1 support person did factory reset of modem. 

when it came back -- they upgrarded something and then guess what 

Modem stopped working.  they spent 2 hrs with me to recover  but all wasted

and in end some one came to call and now he is asking me $129 diagnose this problem. 

First they screwed up the modem, and now they are asking for more moeny 

I feel these guys has no ethics. they just put everythign on customer and if you argue they just disconnect the call. 

if comcast is here then this is oen the complaint no. : CR 431 104 931