Bad service: misleading clients

I have been using this mtn contract for over 15yrs and not even a single month have I defaulted the monthly payment, last year November I received a call for an upgrade as one of my contracts was expiring and I refused to upgrade it then the agent told me about the current one that I am using which is called’sky bronze’ he told me that I can pay lesser than what I’m paying now coz I was paying more than 800 then he said I could pay 499 as my contract is old I have special offers then I agreed coz we all want to save in this financial situation, I agreed with the upgrade then in January my instalment is 2600 I tried to query it with MTN then the nxt thing they told me that I must call Mondo but wen the upgrade was done I was never told that it’s Mondo whose doing upgrades. I called mondo then they told me they will send my query to quality I will get feedback after 2days I waited for over 7days then never got back to me I called them again they told me that the query was closed so the agent checked on the system that her colleague made a mistake then she logged a new query after 3days I just received an sms saying that my dispute was invalid. I requested my call recordings I haven’t received them. I have been a loyal customer to MTN but what they doing is unacceptable.