Promises not kept and incorrect debit order deduction.

I signed for a price lock for R899 in March 2022. The correct amount was taken off in April 2022 but this month the amount deducted is R939. After numerous calls to the Call Centre the issue is still not resolved and no one bothers to call back even after promises are made to do so. When there is mentioned that DSTV is not authorized to deduct the higher amount and that the debit order must be cancelled, they keep saying it is price locked and the debit order cannot be cancelled ????? But no one will fix the error where they are deducting the incorrect amount.