THey have blacklisted me!

I took a cell phone contract and was debited more than the contract and after several call with there legal department, explaining that I am being billed more than what I signed the contract for so I put a STOP ORDER on my payment ... NOW they blacklist me! If you go to the branch were the salesman signs the contract they tell you to contact there head office.. PATHETIC SERVICE, PATHETIC SUPPLIER, There is a consumer protection act if I signed for something how can they charge me extra!