Being charged for a service I have never requested

Good day,<br> <br> During the month of Dec 2014 I did an upgrade through my service provider being MTN. Ever since then I am being charged for a content charge which I \supposedly"requested from yourself.<br> <br> Please can someone contact me with regards to this matter as well as supply me with proof that I have requested this.If no proof can be supp**** I would have to assume that someone is authorizing ********** activity on my cellphone number which has been my number for well over 10years. Without any proof that this was activated by myself I will be forced to take further against your company as well as MTN"""