Terrible Internet Service

I am getting disgusted with Xfinity internet service. About two months ago service started deteriorating. Buffering, stuttering on game playing. About that time 4 and possibly 5 messages from Xfinity that network problems have been detected and that repairs would take hours. Nothing has improved. A technician suggested that I get a new router, $300 later and no improvement at all. In an effort to improve service I upgraded internet from 400mbs to 1Gig and still no change. I run speed tests, I contact Xfinity but the only thing they can confirm is that I'm paying for 1GIG service. There is no way I can confirm that I'm receiving 1GIG. Xfinity is ripping me off and they don't care.