vodacom over charge client when you want to cancel and give them notice over and over again

i have been a client of vodacom for years. On the 30 April i sent them an e-mail confirming i want to give notice to cancel my contact. I also called a number of times in april, may, june,july make sure the cancellation will be processed. They said my last instalment will be july the 25th. They debited my account. Today i get a call saying i need to pay R507 for the month of august. they are adding a whole bunch of stuff that they can't explain why the *****ing from me. Airtime subscription of R285.99 and contract subsidy charges for 199.97. yet my daughter contract was only R299 a month. i want to the branch. They are telling me just to pay. Can't explain. i call the call centre, they moving me to cancellation, customer care, legal. No one can explain. They expect like i am rich. i just go R507 to give away. yet i followed the process. no one know why i was charged. no one is prepared to put anything in writing confirming the reason for these charges. They just asking me to pay. please don't ever take a contact with vodocom. they are prepared to degrade you and treat you bad with you want to cancel the contact. The funniest thing was. i did not upgrade yet because i did want to take a phone at that moment. i was going to decide later. now i will never deal with them again.