overcharged

I recently received a letter that i owe Vodacom R5170.64 as far as I know I had 2 Years contract with Vodacom and I paid every month until the contract ended on 6th september 2018, and ycontinued billing me after the contract ended which I couldn’t understand why. I called your call centre several time ,spoke to Bongani which was a month before the contract ended confirmed will be cancelled,I also spoke to Bright Majola from Northgate, spoke to Tshepo called from Vodacom Northgate,He said I should pay a difference of R200.00 and some rands he said the account will be cancelled month end October 2018.i also have sent a cancellation form twice to your email ********** cancel the contract as I was not renewing ,so where is the outstanding amount coming from.i haven’t received any data or airtime from your network, even the simcard is blocked for months now. What am I paying for.i haven’t used both numbers for long time.i have a bad experience with your poor service I don’t think I will recommend one with your services .