Vodacom doesn't want to stop my expired contract!

I took out a 2 year contract in March 2011 for a blackberry and paid it for the full term (24 months). The 8th of Jan 2013 I got a new phone and new contract at Vodacom for a Samsung S3. I continued to pay the blackberry as well until that contract ended (March 2013). I called Vodacom to discontinue my contract the end of Feb and they told me my contract only ends end of March, which is wrong. My dad also spoke to them as he is the account holder. After struggling to make them understand I went to the Tyger Valley branch and took all the necessary papers to cancel the contract for the end of Feb (a months notice). 2 weeks later I got a sms to say that they will discontinue the contract June 1st. What???. I went in today again to tell them about the mistake and that it needs to end the 28 of Feb. The lady just said there is nothing she could do and that I need to go to head office or call in again. But the people at call centre doesn't help or understand when I call. I have also struggled with vodacom last year regarding a data ****le and I'm so tired of them taking money and giving no service. You easily get a contract but to stop it is a nightmare! So keep your end of the deal!!