TELKOM IS RUINING MY CREDIT SCORE

I took a contract at telkom for R199 for 80GB but never paid that instead they would add things you know nothing about like subscription that sums up to more than R200 excluding the monthly installment of R199 when I contacted Telkom they told me I took up those subscriptions online when I tried to dispute it and told them if I took up those subscription it will show on my phone by getting a notification whether on email or sms they said there is nothing they can do I have to pay the bill and they will cancel the subscriptions which they never did after 3 months I called to complain that I am tired of paying more than the agreed amount so I asked to cancel the account and I stopped paying assuming the account was cancelled because I was getting the data but to my surprise I get a call after 5 months telling me I have pay an amount of R1600 which I know nothing about which means they were still charging me after I cancelled the account so they said they will investigate this matter by logging a complaint for me and i mustn't pay anything till i get a call with feedback but never received it now. TELKOM IS RUINING MY CREDIT SCORE NOW as they sent my account to the debt collectors.