Vodacom Accounts department

I had a vodacom account that was paid in full 2016. Now I hear that I still owe them money, which are more than the amount that was outstanding 2016. Proof of payments that was sent 2016 and now again 2018 did they not receive. Call centre helping with accounts are not helpful at all. For the last month I am struggling to get this account sorted which are suppose to be paid in full 2016 already. I will never take out any contract with Vodacom ever again. Service is pathetic. Accounts department non-existent!!!