Vodacom refuse to cancel my contract

On 2nd April I contacted Vodacom cancelation department to cancel my contract which ended in December 2015 I received a reference number *** and that I should use order number *** when contacting Vodacom and that end of April will be my last billing period meaning 1st of May 2016 I should be prepaid , on the 1st of May I received data and airtime from voadcom which means they did not action my request when I contacted the call centre on 1 May they told me someone removed the cancelation request and when I questioned who had done so the call centre agent was unable to tell me and told me a manager will contact me in 3 days which did not happen and supp**** me with a reference 1-3TF61C3 when I contacted the call centre again today I was again told they are unable to help me , with that being said I received a new reference number saying that my cancellation request is being actioned ***. With all of this I have to pay for mistakes Vodacom made which is completely unfair ,government should review the month to month loophole companies use if my contract is for 24 months I should auto exit at the end of month 24 and not have to write a letter to cancel something that is due to end anyway.