Billing mistake to be refunded and rectified for future payments

There was a R2200 mistake made on my account, which I already highlighted on the 11th of June, on which it was said it will be rectified and the next debit order will be fixed. Debit order went off on the 25th without it getting rectified, and then I was offered a refund on this. Since the 25th I've reached out to customer care and only receive a new reference number each time. I can share the email trail as well as a detailed evidence of the billing mistake made on all my MTN SKY packages on my contract Where to from here ?