Vodacom is a real pain

There's a refund due to me by Vodacom and not only are they transferring me from one person to the next they are also now telling me that they will use that money to set off this month's invoice, I don't remember authorizing anyone to do that! Please just put my money back where it belongs... I don't remember authorizing anyone to do as they please with my money! Vodacom is not a law unto itself you cannot do what you like!!!!! A person can never get a definite answer from you