Mtn bad service again

I had 2 contract phones, on the 18 December 2018 i called to cancel 1 contract as it was about to expire. When i spoke to the retentions department i asked the consultant if December will be my last installment and the answer was yes... January i was then debited for 2 phones i called and spoke to a team leader who told me that the contract last installment was supposed to be Jan and not December i then asked the team leader by the name of Msizi from the JHB branch to investigate and provide me with feedback and after a month he never said anything i then called countless times leaving messages with consultants requesting for call back and when i managed to get hold of him he said he will listen to the call recording and get back to me, the 20 March will be 2 months since I'm waiting for Msizi to resolve my query. This is so frustrating , ive been calling and Msizi doesn't seem to be interested in assisting me. I want Msizi to call me and provide me with feedback