Upgrade Clients Contract without clients permissio

I received 2 phone call from Cell C agency regarding an cell phone contract upgrade <br> <br> 1st Phone Call - I decline the offer, and I told her I will go to the Sandton store myself to get more information<br> <br> 2nd Phone Call - I did not accept anything and the agent put down the phone on me<br> <br> About a hour later, I received a SMS states I have successfully upgrade to a new contract. This is unacceptable and *******.<br> <br> Please may I have the name of the person who upgrade me without my permission and I want to cancel my existing contract with Cell c in immediate effect