After 2 weeks or more of this I called Comcast again. Still got India but this time they told me my modem had been obsoleted by their upgrade and I needed to exchange it.
Got on the website and found the only service center was about 10-12 miles away right through the middle of downtown traffic. I thought that couldn't be right so I called India again the next morning. Yep, that was my only choice.
So my wife and I drove up there Friday and found an empty building with lots of construction going on. There happened to be a Comcast exec in the parking lot and he informed us the "new" service center wouldn't open till Monday. He apologized for the mistake.
So we had to go to their main office. Somewhat difficult to get to because of our screwy streets (a river runs through it) but at least no 10 miles the other way.
Arrived to the usual "take a number" melee with lots of people waiting and only 3 of 8 work stations occupied. After 15-20 minutes my number was called and I went to exchange the modem. The woman asked how I was doing and I explained I'd just been on a wild goose chase to a non- existent office. In her best chirpy manner she responded "Well, at least now you know where the new service center will be".
No, I didn't kill her, although it did cross my mind.