Vodacom Business fails to refund on billing error

In February 2025 Vodacom made a billing error on two of our contracts resulting extra amount of R5 376.25 being debited from our account. I have contacted Vodacom telephonically as well as numerous emails to have the amount either refunded or deducted from our account. I have been promised on more than one occasion that the money would be either refunded or reflect on our account for the next month. Since March this has not happened yet and now, they are not communicating with me anymore. I cannot believe that a refund can take 6 months to issue, and I do believe they are hoping I would give up on requesting action.