Cancellation of contract

On the 4th JAn 2018, I lost my phone. I then went to Vodacom shop to request for sim swap on the 5th. I was then informed that I have a contract with RMCS. I don't remember signing any contract with RMCS. I was then refereed to Edgars or Jet who informed me that they have to call RMCS. They dialled the number and gave me the phone. I was made to keep holding on the phone for at least 40 minutes. Eventually when they answered, I was told that they will revert back to me after 48 hours. I am so dissapointed Edgar's that they gave my particulars to RMCS. It is now five days since I lost my phone but I can't get assistance to retain my old number. I request to be assisted to cancel this dubious contract as a matter of urgency