Happy to gain at the client's cost

I cancelled my contract with Vodacom as their service was **** for long and I also took too long to cancel. This morning I could not make a call and i contacted them and I was told the sim is migrating to prepaid then I asked if my airtime I had would still be available and unfortunately this was not the case. Why r these agents not taught to inform clients of all they need to know when we cancel contracts. Now I have lost all my airtime which I could have used before this migration. This is utter nonsense, so I have lost and they gained. That has always been the case about Vodacom, all they care about is their gains and loss to clients. I should have been informed I will loose my airtime and that my sim might not be active for a period while migration takes place. Will never take any Vodacom products ever except for this prepaid which is my main contact and that's the only reason I will be still linked to them. *** service I must say!