cellc bill me for a phone i dont have to use

I called in the repair center today with the following complaint and issue I have with cellc constant ignorance towards my issue I have with my blackberry device.I took the cell phone upgrade at the end of March for the Blackberry and from day 1, I always had an issue with the phone being too slow, unresponsive and the battery dies to fast.I eventually at the beginning of July logged a call with Cell C to take this phone back and hand me a new device It then took Ram 2 and half months to collect the device.They eventually collected the phone at the beginning of Sep and its now the beg of Oct and my device has been with CellC for 1 month, they blatantly ignored my request to give me a new device and repaired it by replacing the mother board and upgrading the software, Cellc is very quick to debit my account every month on time even though I don't have a device to use, isn't this absolutely ridiculous and *******, you people rob us innocent citizens and eat our money and not provide a good service and proper devices.I will Sueue cellc and take then to court as they performing bad practice by billing me for something I don't have and can't use.I want a new device or I will cancel.