Disappointed with Vodacom after paying my contract for 3 years and Rude consultants

What a terrifying service i get from Vodacom Terrible and upsetting after paying Vodacom for 3 years without missing a single payment and when the contract ends now in May ,i am told that i will still be deducted for two months because i did not call vodacom to call the contract although I had agreement with them for a term of the contract, The call center agent were very rude and telling me about being placed in bad credits while i have been paying for 3 years month month without errors, and the only thing they are concerned about is me doing and upgrade, How do i upgrade the contract with a company does not care about the interests of its own customers Bad service now after such a long time of being your Customer