Vodacom taking their clients for a ride

I have been a loyal Vodacom customer since 1996 and one would expect that being a loyal customer for 21 years would count for something but apparently not. At the present moment I have five seperate contracts with them. Due to costs I reviewed what I have and came to the conclusion that I will have to scale down. I have since given notice of the cancellation of one of the contracts to vodacom, lets call that contract (A). I still have airtime and data available on this contract and asked vodacom to please transfer it to contract (B) which is still ongoing and in use. I was told by the lady at vodacom Mossel Bay that this cannot be done. My question is this. The said airtime and data was purchased and paid for by me. It thus belongs to me but I cannot use it??? Let me add that contract (A) is still alive and will expire end August 17. I really think this is rediculous and boils down to theft. Both these contracts is in my name and paid for by me.