Cell C bullies!

Cell C are bullies. After a month of phoning and begging them to honor our contractual terms, they cancelled my contract without consulting me. Cell C overcharged me for 12 months. When I complained, instead of paying back my money they they simply cancelled my contract. I basically paid off a 24 month contract in 12 months. They are the only party here that benefits. How is it that big corporation's can just simply go ahead and treat their customers like they don't have any say. Hello....... Cell C a contract is between two parties. Did we discuss your proposal and did you give me a opportunity to give inputs??