Cell C - The WORST network provider EVER!!!!

The last week in March, Cell C contacted me to prompt me to upgrade my phone. I eventually agreed. We went through the whole process, and 24 hrs later they delivered the wrong phone. Within a day the courier fetched the phone from us, and we didn't hear from Cell C again - only to notice that the amount for the new phone has been added to my bill. I contacted Cell C again the first week in April, who said they first have to reverse the first upgrade and then start from scratch, which they then did. After another two weeks of not hearing from them, I phoned again. The reversal hadn't been done yet. Another two weeks go by... On Friday I had enough, I just want to cancel my contract. Guess what - they have to reverse the upgrade first!!! I was on the phone with Cell C for 45min, during which 3 people told me the upgrade had been reversed and 2 said it hadn't. In the end they promised to phone me back that same day - they didn't. Today I phoned, just to find out it's going to take 30 days to cancel my contract. And they're still adding the amount for the new phone to my bill!!! Oh, and did I mention all the while my phone is inexplicably eating data, and I don't know how to stop it.