Robs customers

I did a renewal of my Vodacom contract on the 15th March and received my new phone and did a migration from the Uchoose Smart M package to a Uchoose flexi 200. I was informed the new contract will take effect on the 1st April and i could continue using my minutes until the end of the 31 March. But on the 31 March i lost all minutes and was told i will get new airtime allocation the next day. My question is what am i suppose to do on the 31st March? why wasnt i told i wouldnt be able to use my minutes and airtime on the 31st March. I just lost all my minutes which i already paid for.... please explain why you are robbing people!!!!