Vodacom is a **** dont take their contracts

My account was handed with a wrong balance of 48mnths which vodacom was suppose to correct and never did now am being harrassed by SAYA RECOVERIES claiming i owe vodacom R3576.58 which is wrong aas this money is calculated on a 48mnths contract which when i took the contract it was 36mnths i have been asking Vodacom to fix the problem and no one bothered to assist instead i was sent from pillar to post can correct figures be sent to Saya Recoveries