I actually just ditched AT&T. Not only were they throttling my data speeds around Manhattan (I was grandfathered into an unlimited plan but was using well below 3GB a month, the threshold past which they claim to start throttling) and making my iPhone virtually unusable at times, but I had a customer experience with them that was so bad I could not stay with them a second longer.
Basically I had wanted to take advantage of their iPhone trade in promotion to upgrade to an iPhone 6 and get $200 credit for my 4S. They botched the application up (I was never emailed a promo code) and what should have been a quick phone call to customer service to sort this minor issue out turned into an epic 3 hour call which ruined my Sunday afternoon. They passed me around department after department because not one of them knew how to deal with it. They put me on hold for 15 minutes at a time hoping that I'd hang up, then they'd tell me that such-and-such department would definitely be able to help me, and after another 10 minutes on hold I'd have to explain the whole thing again to another bozo who made no effort to even understand the problem, who would then go and "speak to his supervisor" and put me on hold again. And on hold, I'd be subject to this endless recorded loop of a bubbly woman with a grating voice breathlessly telling me about all of AT&T's offers and promotions and how good their network is. It got to the point where the timbre of her voice when she said "AT&T" cut through my ear drums so painfully that I never want to hear that name spoken again.
After 3 hours, they put me through to someone who not only didn't understand my problem (and didn't care), but also informed me that my online order for a new phone, for which I'd been sent a confirmation email (and every other rep I'd spoken to so far had confirmed it was OK) was actually invalid, and that I'd have to go down to my local AT&T store with 2 forms of ID in order to sort it out. I told her to cancel the whole thing and gave her the most eloquent tongue-lashing I've ever given anyone in my life.
The next day I walked into a Verizon store, signed up for a business account, paid for a new phone and went home and completed their trade in application, which went off without a hitch. Then I found an article on a popular tech site in which they tested download speeds around Manhattan with all of the major carriers and found that Verizon's speeds were in some cases 4 or 5 times that of AT&T in New York. Can't believe how much I paid AT&T for so long for such a piece of crap phone service. I'm under no delusions about Verizon - no doubt I'll have some terrible CS experiences with them too - but right now I feel like I've just gotten out of an abusive relationship and am dating someone awesome