MTN just keeps taking my money regardless...

For several months MTN has added "Content Charges" to my monthly invoice. I have been in pages and pages of correspondence with MTN's Customer Care department. They completely deny any responsibility (although they are taking this money directly from my bank account each month) and direct me to Waspa. Waspa has provided me with written proof that I am not subscribed to any third party content. I have provided this proof several times to MTN, but they ignore this and keep re-directing me to Waspa. I have also visited MTN stores to try to resolve this and each time they check my phone and confirm that I have no third party subscriptions. But MTN continues to make "Content Charges". Nobody is listening at MTN. Their responses are insulting and, surely, *******? Does anyone know how to resolve this issue?