If you feel as if the cell phone companies have ever let you down, not held up their end of the deal, provided poor customer service or data service, or just out-right lied to you; check out this FCC Complaint Form.
If enough people actually complain to the FCC, they may figure it out and actually do something about it. If we do nothing, nothing will change.
This form is a pdf (portable document format). It includes instructions on how to proceed.