Pathetic customer service

I have called Vodacom customer service from the 26th of June up until today the 21st of July and still calling, at least 10 times a day buy time no avail. I am trying to get my refund for an overpayment. When I finally get through I get transferred to the relevant person but the call is always disconnected and I get cut off and nobody bothers to call you back. I have spoken to the Vcontractor manger and was told that the money will be in my account by yesterday. Nothing up until today. I have left messages. Sent her emails and no reponse . What do I do. There service is pathetic. I give up. Not sure what to do. I think I'll just stop paying them and cancel my contract with them .