I'm not quite sure why Comcast hasn't emiserated the in-store situation yet
There are practical limitations in a brick-and-mortar situation. There are a limited number of behind-the-counter folks, and having to hassle a not-gonna-be-a-customer for an extended amount of time makes the lines at the counter grow and grow. Since it's the same counter (and workforce) used to generate business by selling hardware and service, it's counterproductive to sabotage that by extensive "retention" operations. Not to mention that the desperate, wheedling, infuriating conversation that results would be witnessed by everyone else in line; and no matter how dumb, most of the mammals in line may notice that and wonder if doing business with Comcast would be such a good idea.
Whereas a boiler-room telemarketing op has none of these risks and liabilities.
Moral of the story: deal with Comcast where they have some incentive to deal decisively: their own showrooms.