Useless Company

Vodacom is a useless network provider in South Africa. I had a 2 year contract with them and I cancelled the contract in September 2018. They sent me a quotation for the amount that I must pay and I paid the amount. I sent them the proof of payment. Now suddenly in June 2019 I get a final demand letter that I must pay R463 that is in default. When I call to find out what the amount was for they told me that they forgot to cancel the contract in September. after cancelling the contract I still received the normal airtime and as it was my first time cancelling a contract no one explained to me that I will lose the benefits hence I never queried. Now I must pay for your incompetence? if you had done your job and cancelled the contract in September none of this nonsense will be happening. Now my credit score is affected because of this.