Contract from hell

I took out a Vodacom cellphone contract in March 2016, contract was set to end in March 2018. I informed Vodacom in February 2018 that I would not proceed with the upgrade therefore I requested balance on the contract. The consultant I dealt with insured me that once I had informed them of the termination the contract agreement would be terminated. I made the payment of the outstanding balance on the 28 March 2018 an amount of R498, as per consultant's advise. After the payment was made I received a sms confirming payment, I decided to call Vodacom requesting an email address where I could send proof of payment, which was given and sent as well. I called them once more requesting a paid up letter on the 29 March, I was told to call after April to request the acknowledgement of payment letter. On the 3 April called requesting acknowledgement of payment letter. Which I am yet to receive. To my knowledge I have paid up the balance and any outstanding amounts but on the 3 April a debit order of Vodacom went off questing an amount of R498, I contacted Vodacom about this, I was told I must pay that amount of R498 an additional R100 for the unpaid debit order. I do not understand how this company works, this is modern day *******.