MTN Spam Messages

I am writing this to complain about MTN who I believe is not adhering to POPIA.

I currently have a cellphone contract with MTN for 2 phones and 2 SIM cards, my second phone is being used by my daughter. Since taking out the contract I have been receiving spam SMS and USSD marketing messages from MTN which I didn't sign up for. Especially the USSD messages are very misleading and have caused myself and my daughter to accidentally subscribe to services that we don't need or want.

I have phoned MTN Customer Service and explained the situation to them that I am not interested in these products and the person told me that she will remove me from this marketing list. But this has not been done and I am still receiving USSD marketing spam messages.

I don't know how to handle this further as I have tried engaging with MTN directly but this is not helping.