Sorry, have to chime in here. I was throttled, been with AT&T when they were Cingular. I never once went over 3GB cellular data, not ONCE. I was throttled Oct 2011 - Jan of this year. The most data I used was 1.87 GB/mo (I'll never forget that figure). I was in San Francisco on business and interviewing, when AT&T throttled me. I calmly went into the nearest store on Market St. and spoke with a rep. The rep was surprised to see a notation on my account, and he couldn't do anything without calling in (he was perplexed). After over three hours of trying to understand why they put a hold on my account (never missed a payment, automatic payments), and never abused my data, neither I nor the store reps could understand. I have a 917 number, NYC market, which is the only thing they could consider.
As I need voice+data, I'm stuck with AT&T's GSM network (pissed they didn't include a proper radio chip for Verizon to have LTE voice+data, I don't buy their excuse, Broadcomm has had a proper tri-band radio chip for a while and could have easily fit, my guess is AT&T made a deal with Apple to keep that one edge over Verizon). AT&T's service has definitely improved, however they are a bunch of crooks. They throttled me so much I couldn't check email, even my visual voicemail was down. I was forced into taking a 3GB tiered data plan, the second lowest was too low, I barely use 1/3 of it.
I am not an exception. I recall many were experiencing this issue around the same time. During one of my many calls to AT&T customer service, I remember the rep stating (and I paraphrase) this "program" may end at any time when asked when this may come to a stop. She caught herself from going off cue.
The FCC should seriously examine the North American mobile phone market. The rest of the world pays for plans on SIM cards and can use any phone. No contracts, just pay for more service on your SIM card account, drop the SIM card in, and on you go. ETF's, two year subsidized phone contracts, price gauging - it's business and these corporations will do anything to keep the customers from having any power with less choice (thank GOD AT&T and t-Mobile didn't merge, the only GSM networks in the states). I would gladly pay more for a phone with the freedom to choose my network (heck, I paid $399 for my iPhone 5, and sold my 4S officially unlocked for around $350). This crap needs to stop.