MTN is robbing me

Myself and wife have been loyal customers for well over ten years with MTN ,however I experienced a issue where my monthly anytime airtime minutes was reduced from 150 to 50 for 2 months I couldn't believe it at first and I checked my contract etc. After gathering all information needed I thereafter called the customer service team on the 16th of December . The lady that assisted me told me I was in fact wrong and I have always just been receiving 50 anytime minutes ,me all confused and couldn't understand why she advised me she was looking at my account and can see it's always been 50 anytime minutes . I called up again on the 12th of January because I knew I was **** to and couldn't have it left not sorted, the agent that assisted me advised me I am correct I was to get the 150 anytime minutes as that was my contract agreement ,she followed the necessary steps and told me i would be credited with the 200 minutes that i was owed for November and December. Got a SMS confirming reg number and that it would be sorted within 48 hours she also gave me the ref number call time date and the agents name that **** to me on the 16th December. I recieved my correct figures for january but still no feedback as to what was owed .I called up again waited almost 20 minutes and given no answer asked to speak to a manager the agent said that the manager is busy and would call me back that was Wednesday and still nothing .I am furious and frustrated, being **** to I was even given 2 email addresses and both no response