Vodacom are com artist

I had a cellphone contract with Vodacom my contract ended and they never stoped it. They loaded airtime after it ended then I used it. After using it I received a call from them telling me that I have to pay for it. I then told the consultant that I will pay it because I used it, then asked him to cancel it because I no longer need their airtime and my contract has ended he told me that they can't cancel it. Now my line is blocked I can't make or receive calls and my bill is over R2000.00. I would like then to open my line and they must sort out their mistake. So guys I advise you not to buy contract phones from Vodacom cause they are con artists.