Contract cancelled mid day

I instructed that my contract be switched to prepaid on 1 Feb 2015.<br> I was instructed to switch my phone off at midnight and it will be on prepaid the next day.<br> Today (31st) my contract was cancelled midday (around 13h00) whilst I still had data and minutes left??? That is unacceptable! I paid for that data and minutes and it is not even close to the end of the day?!<br> It seems very convenient to Vodacom to cancel the contract midday so that they can score the unused data and minutes!