Difficult to obtain refund

This is being posted here because I have exhausted all avenues viz the call centre and cell c stores. A data contract had ended and I had decided to fully terminate that contract upon expiration as it wasn't required anymore. The final debit was in December 2018. In January I had received a statement stating that I was owed an amount of R146,14. I had contacted the call centre and they stated that they could do nothing and that I would have to go into a store personally. When I had done so, they had stated that they also could do nothing and that it would have to be done via the call centre. I understand that this is a minimal amount but it's the principle of the matter and it's money that's being owed to me. I will be greatly appreciative if a resolution can be reached