Incorrect Billing and package

I am so tired and disgusted in Telkom, i have spent endless calls trying to get my profile sorted out. My Telkom landline subscription has been upgraded without my permission. I called and asked for it to be changed, a credit was done but subsequently i am back on that option and i am being billed and am in arrears because i cannot afford the option that i was placed on. I would like to submit 30 days of cancellation on my Landline . I am so tired of trying to call because nobody ever answers ! I want this cancelled immediately because now i have a negative credit score due to Telkoms fault of incorrect billing. I need this resolved. The last person i spoke to said she would arrange for everything to be changed but nothing has been changed. I dont use the landline , i dont receive calls or make any so i am actually being billed for a service that is not even in use. I need this looked at urgently