No network since Thursday

My sim card has had no network since Thursday the 31st of March. I called vodacom customer care a number of times to resolve this issue but they kept sending me from pillar to post by transferring me to different sections which did not help me. My sim card was a contract sim which expired on 31-03-2016 and was supposed to be converted back to prepaid upon expiration. To my disappointment this has not happened regardless of me following the correct procedure in doing so. I am not happy at all with the service I have received from Vodacom. I have had to use an alternate number these past few days because my original number is not working.