Incorrect contract period captured.

I am not sure if you are aware that MTN has brokers that call their clients towards the expiry date of their contracts for an upgrade. I had my second contract with MTN which i took out directly from the store back then. Towards the end of it in 2017 October-November I received a call for an upgrade. I agreed to the upgrade for a Samsung J7PRO since the person who called was promoting that but had a specific condition that my contract should exactly be the same as my previous one which gave me 300MB, 100 minutes and i think it was 50 SMSs. Then i also said that the monthly installment shouldn't be above R 300 and if it was she should offer me another Samsung phone for the exact package but not more than the R 300. I also confirmed if the calls were indeed recorded since contracts concluded over the phone usually have loopholes and the lady confirmed that it was. A months down the line i am receiving a different package which we did not agree upon(100 MB, 50 minutes, 100 SMSs). When i called back to correct it i was sent from pillar to post and was told that I should speak to Maria who assisted me. At the end i just gave up because i couldn't find Maria and carried on with the contract since the data didn't affect me that much. Come 2019 June, knowing that my 24 months contract will expire soon i called and asked if i am allowed to upgrade before my time and the 1st consultant said yes and transferred me to the upgrades' department. Now this department shocked me because they said i am not legible to upgrade because my contract is very far from the expiry date. I then asked how that was possible because MTN contracts are for 24 months and when I took out mine I said it should exactly be the same as the previous 1 which was 24 months as well. Then the guy said on the system it says my contract is for 36 months, i disagreed and requested the recording. To date i am still waiting for it. Every time i call i am still sent from pillar to post. The last consultant promised to send it within 48 hours latest was after 72 hours. I still haven't received it and my contract on their system still says 36 months instead of 24 months. I want it cancelled. To be honest i am very very disappointed in the service MTN provided with regards to my current contract with them. I have never had any other cellphone contracts with any other service provider either than MTN because i valued their service and loved their benefits but this time i am singing a different song especially because their consultant didn't disclose important information such as the insurance, contract period and the full package it comes with. MTN must change my contract to 24 months i will not pay for a cellphone like i am paying for furniture. They should allow me to upgrade after my 24 months lapses and not later than that. I still want the recording because that is my only proof of the contract.