High bill received after contract came to an end

Before my contract came to an end Nov 2015 I made countless calls to CALL center asking them how there policy worked when 24 months contract ends.They assured me that I will not be charged for extra BUT when I received my account it was R1331. I was only supposed to pay round R250. I decided that I want to cancel my contract I emailed on the 15th Dec, they read on the 16th Dec. I received a call on 17th Dec 2015 from the retention dept confirming to me that they made mistakes with many customers with their bills and they promised not to deduct that amount off my account but they **** and deducted the R1331 on 31st Dec. Since then I have contacted their customer care on 081 180 every three days to find out the status to no avail. I have to repeat my story over and over to different agents. I received my new bill on the 2nd Jan 2016 and its R934 which is too high as my contract amount is about R758. The call center agents dont know their job and lies to the customer. On 2nd Dec 2015 I received a sms saying that they will refund me but nothing happened. Im tired with Telkom and want my refund and also want it cancelled. All they did was lie if i knew i would have cancelled long ago