BAD SERVICE

I had a contract with MTN in 2018 , took an iPhone7 plus insurance. June 2021 was my last payment. I was advised to cancel the insurance and same was done and I got a reference number on a sms. 2022 I received a call from Collections company advising that I owe R538.00 for that insurance as it was not cancelled. I lost the phone were the ref was saved in 2021 December. I paid that amount. 2023 I received another call from Very Cred advising I need to pay settlement of R738.00, I paid again and I asked for a paid up letter this time and a statement was sent to me. I email TRANSUNION for a Credit report ,all to find out I owe MTN R3500. I Paid that money in installments now they are sending me from pillar to post for my paid up letter. MTN SOUTH AFRICA, I WANT MY PAID UP LATTER NOW!