You’ve just gained a legal leg to stand on.
Judge Russell Nadel awarded Matt Spaccarelli an $850 judgement against AT&T because his iPhone’s data was being throttled even though he was on an unlimited data plan. Class-action suits are verboten under your contract with AT&T, so you’ll have to take them to small claims court just as Mr. Spaccarelli did.
Now, under your contract (according to the AP, I haven’t dug through mine to verify yet), you may as for damages up to $10,000USD. What Judge Nadel did was award Mr Spaccarelli $85 for each of the remaining 10 months on his contract, plus $85 for court fees. AT&T has decided not to appeal, and quickly cut Mr. Spaccarelli a check, which he tweeted as proof.
Do you want to take on Big Blue, too? Normally, AT&T would make a plaintiff sign a gag order to get a check, but Mr. Spaccarelli declined to sign and they paid him anyway. And he is working on putting his experience on the web to help you do it, too. Pay his travel expenses and he’ll even be an expert witness for you.