Over billing on contracts and inconsistent amounts on statements

They busy over billing people in their contracts, when you ask them how far are they with removing a contract that has ended they give excuses so they can continue billing you more. Whats worse you never know what you paying for as each month the is either an increased amount in your statement. Their statement are always inconsistent you find yourself paying for more than what you are contracted for. Their finance department is busy ripping us off instead of listening to us and giving us clear explanations as to why every month the statement is different. I hate vodacom for this. Instead of paying for two contracts they make you pay for 3 even the one that i have cancelled