Bad service by Vodacom after being after using their network for more than 20 years

I thought my contract issue was resolved until I receive another message from Vodacom that say I need to pay them at the end of this month, of which I paid them fully for cancelation that was not attended and resolved proactively by their staff not even getting a courtesy call from them but when they sell their products they will call now and then. This is a very bad service from a world known service provider.