Appalling Service

I have received the most appalling customer service from cell c. I have been with Cell C for about 12 years. I was due for an upgrade in January 2015, I have been in contact with call centre since March in regards to this. I am always cut off or advised that the consultant will come back to me in regards to my upgrade opinions but this never happens. Managers are never available irrespective to what time you call. I have tried at 8am, 7pm or during the day. Clearly there is no management at cell c who gets back to consumer or assist. My contract ends on the 27 April and I asked to be converted to pre paid but Cell C now wants a month's notice. I have asked 3 times today 24/04/2015 for a manager to call me, I was told they would return my call at 11am but no luck. I just received a sms stated that my contract will be terminated on the 24/05/2015. This is not what I asked for.