Unauthorised deductions off my account

Unauthorised charges on my account - to the value of R71 in Feb and R588.56 in March under Content Charge. Who gave them permission to charge me for unsolicited sms for services. I contacted the call centre and was told the charges are for services I subscribed to fo games??? and prizehub. I have never subscribed. It appears that if you go into a web they send you an sms with a daily charge, If you don't see it and respond with STOP you get charged. MTN can not provide you with proof you requested the service. How can they deduct of your account without your consent for a service they have no proof you requested. I was given a number to phone to cancel and spoke to some Chinese women who when asked what service is this she kept saying send an e-mail if you want to complain. MTN agent then tells me they will load a service on my account from preventing this from happening again. ***!! I want a refund. MTN should not deduct of my account for a service I never requested and they cant prove I did