So tired of bad service

I have been with Cell C for at least ten years and unfortunately I always tend to give them the benefit of the doubt. Unfortunately, my bad experiences continue. I called them today to ask how I could pay off my contract on my iPhone. My contract was renewed around March. When I called to enquire, I was told that since then, my contract has not been updated and I'm working on a day to day basis apparently based on my last contract that was for a Samsung. My account has doubled, and I have enquired twice on the reason. Not one time did anyone query that the phone was on my old contract. Unfortunately I'm unable to open their emailed statements, yet another thing I've enquirer about. So I can't see my billing. When I asked how else I could receive my account, I was told I must just download the software, which I explained I can't on my work laptop. This is over and above previously being billed for two devices I never received. Over and above being given this new phone too early and then not being able to activate it. Over and above being given a faulty sim when I finally reached the date I was told I could now activate my new phone. Over and above the terrible reception. Over and above broken promises and lots of my own airtime I've spent trying to get answers over the years. Can I please just have the account I must pay to settle my not so new phone, so I can finally call it quits with a company that has proved over and again, that they are not in the business of servicing and maintaining customers.