Disappointing Vodacom

Pity that the stars could not reflect a negative. I requested a settlement invoice to cancel my contract on the 25th of April 2018. This settlement amount was then paid on the 27th of April 2018. Today ( 25 Sept2018 ) I received a sms stating an account balance which I could not understand- so I called Vodacom to find out what the reason is. Only to discover that the contract was still not cancelled and that they just kept on billing me and putting airtime on a number I don't use and asked to cancel AND paid the settlement amount? 100% indication of a money-hungry company that will exploit their customers at any given chance.