unauthorised actions on my own private number

January 2014 my own personal mtn pre paid number ***)was switched from pre paid to contract by Samantha at mtn springs without my consent or even me present at the store. Then a week ago this same number which has been switched to contract without my consent was stopped. when I went to mtn springs the avenues last week I was told by Paul that this number was cancelled by the contract owner. My question is thus how can Samantha at mtn perform actions on my number without my consent meaning anyone can go into mtn and activate/ cancel or do whatever on anyone's number.Iis that not why we rica our sims so that it is secure and safe from other people. I now have been without a phone for 2 weeks due to this. All my bank sms's and everyone has this number. I want this number to be put back to pre paid but was told I cant. I cant put MY OWN number back but someone else and SAMANTHA at mtn can do???? Does this make sense? I will have to open a ***** case I suppose.