MTN Subscription **** on Contract Sim Cards

What MTN is doing is ethically wrong. I have had a very good customer relations with the provider up to this point where they subscribe my wifi sim card to unknown content which I didn't sign up for and now when I recharge airtime to the number they deduct money from my number .When I called the call centre I was told that I'm responsible for those charges because I somehow signed up for it. I wish to cancel my contract with them but I cant afford to do so because of contract cancellations fees but as soon as the contract is due for renewal I will not renew my contract. It's sad that a company that I have preferred over other service providers is *****ing people's hard earned money which they cannot explain why they are unduly benefiting from things customers did not sign up for .