Yes, I'm sure somewhere, someone is trying to start a class action lawsuit against, Sprint. I'm sure there are people trying to start class action lawsuits against Verizon, T-Mobile and AT&T as well. That's how things go.
Two things about this though, I really doubt anybody who voluntarily signs up for an extra service charge would win a lawsuit that they are being charged the the charge they agreed to be charged.
Also, class action lawsuits usually don't do much for the people suing (monetarily at least). Most of that money goes to lawyers, remember the Music Industry one? People got a free CD voucher (not even cash), and they were paying about $5 too much per CD for about 10 years.
If a company ever screws you over to the point where you actually sue, its sometimes better that you were one of a few that got screwed if you're looking to get rich.