Pathetic service by vodacom!

Hi my name is yacoob. I had a contract with vodacom and the last month when I called to terminate this contract by giving them notice that I do not wish to renew my contract. At this time I was speaking to an operator from vodacom and did ask her if my airtime I had gets void when contract expires or does it just stay when I move onto prepaid. She had adviced me clearly that the airtime when my number moves onto a prepaid line will still remain.. When the contract did expire the airtime dissappeared. I then called vodacom on several occasions to check what's going on and hear the telephonic conversation.. No reply or return of any calls or queries.. I made many calls back to them to ask for a feedback and no help yet till current although the query was finally escalated last month.. But still no proper response was received. I will never take out a vodacom contract again as the service is pathetic..