Refund from a bad internet service provider

I am waiting for a refund that is due now for 3 months. Every time I call they say they will email the accounts department and every time they say it will take 21 days. Called today again and they say they are waiting for a refund approval and a mail has been sent again to the billing department. It is easy for them to take your money every month but you will always struggle to get refunds from them. It seems they are 2 different company's not communicating with each other. I always ask for feedback but never receive anything. It is sad that companies in South Africa don't believe in customer service anymore. I blame the bad managers.