Unfair billing for things that happened before I entered into a contract with MTN

Customer service unprofessional and failing to uphold TCF principles. Making me liable for the cost which were due to their failure to do due diligence. I entered into a contract with MTN on 03-12-2025 for a R149 per month simcard and router but MTN gave me a simcard which ahd already a pre subscriptions add-on which were charging me R7/day each. When I inquired about the high billing cost they said I subscribed to this third-party add-ons. But further inquiries revealed that the third-party subscriptions were auctioned on 18-11-2025 before I received the simcard. When I challenged the billing and these add ons, they blame me for it and indicate that I am responsible for the cost. In addition to that, inhave never inserted the simcard to my cellphone device and this simcard has since been in the router yet they still blame me for the 3 third-party subscriptions charging me R7/day each. MTN must correct the billing and reimburse me accordingly.