Since December 2014 waiting for refund

I booked a return trip via the call centre where my credit was charged however i used one trip and was that i can used the other trip anytime in 6 months which was ok however when it was the time to use that trip i was told that we will charge you again and refund you the other trip that was the 8 Dec 2014 the R412 until today i have called them numerous and everyone is taking my details however no feedback on my refund that money has generated interest for Greyhound which is also due to me