Playing hide & seek with my refund!!!!

I paid Cell C and they still debited my account for the same amount, now they refuse to refund me it’s a story after another - I am on the 8th reference number now and they all get closed without processing the refund. They acknowledge my request for a refund but close the call without processing the refund. Every time I call to follow up I I’m asked to send proof of payment which I sent two weeks ago already and I’m always assigned a new reference number and told the process will start from scratch. I am frustrated now as this is affecting my financial planning. How will I be able to keep up with their payments with this drawback in my finances?