That's funny, I regularly say please give me a discount or credit, politely, in person, emails or on phone. For the last four times I can remember, the CS rep was always nice and on top of that, does it.
In my experience anything even a little more "targeted" tends to have more reasonable customer service. I've had good customer service experiences from major sportswear brands, and we're not talking crazy high-end, boutique brands but major, publicly traded companies. That isn't to say they will just cater to your every whim, no questions asked, but if you have a legitimate grievance they will handle it without ruining your day.
Some companies care about reputation and customer satisfaction, and some just count every bean.
* not a shill for Comcast, just a happy customer. I tend to be extra-friendly over the phone, which maybe helps, but I have always received stupendous CS support from big corps like Apple, Comcast, Sprint, my CC companies, mortgage holder, and Amazon, to name a few I have dealt with regularly.
When I lived somewhere where the only alternative was terrible 5mbit (advertised, actually much less) AT&T DSL, they wouldn't extend any of my discounts and even when I canceled they didn't even try to stop me. They basically just told me "haha good luck, you'll be back".
When I've lived in other places where there are options like webpass or fiber, they behaved much more like you're describing.
And as I recall, I had put a block on my credit report, so it took a few calls to the sales agents to close the deal. Each one was equally willing to deal, but then again, each time I called back I had to give more to get the same deal (1 year to 3 year, 100$ product gift certificate gone, and finally no free installation—uuug! They said I had the GC, but it never showed up. I called, they stalled, whatever)