Over billing and illegitimate promotions

I have been a loyal cutomer of AT& T for years.  In February, I removed the promotion for Cinemax and HBO along with HD from my plan.  I was told that I would be reverted to my previous plan and I specifically stated that I do not want any promotions from AT&T now or in the future.  I paid  $79.38 in March 2013 after the promotion was removed.  I paid 97.15 in April and then I started to become concerned. When my May bill came it was $119 and some cents.  A call to the billing department did ot help because I do not know what they see in their system.  She told me that a promotion for U-Verse was taken off and so my bill has gone to $85 and some change.  My question is why I have paid three different charges for U-Verse for March through to May. If I requested that I return to my original plan, why was a promotion removed to have my bill jump to $119.00 for internet and the 200 channel package? My internet charges remain the same.  This is a recurring problem with AT&T where drive up your bill and then offer promotions to lower it and then the roller-coaster ride begins. They often ask me to include my cellur device to AT&T but I will not leave Sprint since my bill with them for the same service has remain stable for over 10 years I have been with them.  I am contemplating filing a class action suit against AT&T because this iBig Business highway robbery.  There seem to be no recourse when you call in to customer support.