If you thought Sprint’s customers were bad for calling in 40 times a month, you should check out some AT&T customers who are participating in a class-action lawsuit that’s been on the ropes since 2004. The plaintiffs claimed to have been overcharged by up to $40 monthly by Cingular. It was decided today by the Washington State Supreme Court that AT&T’s stipulation in the end user contract which forbade customers from filing class-action suits was unfair, and undercut Washington’s Consumer Protection Act. As a result of the decision, the plaintiffs can move forward with their case in county court. Busting down the ban could set an example for other courts to follow in similar cases where carriers are screwing over customers.