VODACOM OVERBILLED ME NOW MY CALLS ARE REJECTED

Vodacom overfilled me I have decided to do a premature cancelation of which is all the necessary payments were done I came to realise that vodacom only closed one number now when ever I phone them to fix my Installment i am receiving different responses. Of which is they don't even make sense they are trying to cover up their tricks. Now recently when I phone they are dropping my calls.