I'm sorry to hear of the problems you've had and would be happy to try and rectify an issue if you're still having one. I am a proud Comcaster (Faster, faster, you're a Comcaster!)
If you are still having an issue just contact me here... I'll give you my RL phone and we can take it from there... I can have an escalation tech call you.
As both a customer and an employee I've always had excellent customer service and experience with all of their products. I use the Digital Voice service for phone, High Speed internet and their cable service.
And since I've worked in the industry for the past 15 years through many different owners I can say categorically that they are the best of them so far. AT&T Broadband farmed out their tech support to India - Comcast does NOT. It's done locally by people who are your neighbors. TCI seemed not to care for customers. Comcast has extensive training for all their employees with a high emphasis on customer service.
Do they make mistakes? Yes. Do they do their best to fix them? YES! Do they care about their customer base? YES!
Think about this... if Comcast only makes mistakes with 1/10th of 1% of their customers that's still thousands of people they goof up with. Any other industry that had a success rate of 99.9% would be considered AMAZING. But due to the large customer base, those angry people can create an image that goes beyond the reality for the vast majority of folks.
Regardless... I'd be happy to try and help if you're still having issues.
...Comcastic...