Not able to cancel contract after asking numerous times

This is for Vodacom Cancellations. The tried to cancel the number *** in Feb, March and April. Feb they told me it was too early, I must phone in March. Then I phoned in March, and they said it was still too early. The I phoned the Accounts department, and they said I CAN cancel it in March, so I phoned the Cancellations dept again in March. The guy said he can't cancel but he will make a note for 1 April. Then in April, I decided that I don't think this guy is going to read his note, so I phoned Cancellations AGAIN to cancel. They confirmed that end April I will pay the LAST payment. And then, in May, I still got the amount of R339 for this number on my latest account!! Shame on you, Vodacom!! Today I phoned Accounts again, they said Cancellations DID NOT CANCEL the contract. I also sent an email query earlier this week, but NO REPLY after giving my ID, account number and bank. So I decided I am not going to spend ANY more time on this, this will be the last. Vodacom, please cancel contract number *** for end April and deduct the R339 from my May account!!!! As requested 3 times. Please go and listen to my recordings before you phone me.