How is it possible to subscribe to something without the necessary permission

My son is subscribed to something not sure what and extra charges has been charged onto his Telkom cell phone bill. He has not subscribed to anything that he is aware of. On my enquiry to Telkom it show that it is with your company. For 2 days in a row I have sent mails and tried to contact Basebone, but with no luck. How can he unsubscribe immediately as this extra cost cannot be carried by him as he is a student.