Refund still not paid back to me afer almost 2 months

The service that I am receiving from Vodacom after having a contract with them is very bad. I had a contract with them which I cancelled in March and paid them the full amount quoted by them. Then I received a statement from them in April that I still owe them money. I called them to try and sort it out before the money gets deducted off my account. But no feedback received from them, as no one knew what i was billed for. Then the money was deducted in May. And since then I have been calling them to refund me the money that was wrongly deducted off my account. The worst thing is everytime I call the stuff that needs to be prosessed is not prosessed on the day I called and then I must wait longer. It was very easy for them to take my money that did not belong to them, but now I need to fight for more than a month to get my money back. I have had enough of there poor service. I will never open an account with them again after there poor service. I just need them to pay my money back asap that does not belong to them, before I take this matter even further.