Misleading Contract Offer

I took a contract in 2017 with MTN and I cancelled it after expiry. When I was cancelling I was offered a contract where I'd be given 50 minutes and 1GB of data. The person I spoke to said it was a month-to-month contact but when I was cancelling it I was told it is a three year contract. The worse thing is that MTN does not send the written contract after agreeing on the phone and the guy I spoke to when I wanted to cancel did agree to send the audio of the agreement that would prove that I am not lying. I have been using MTN since my first phone but now I feel my loyalty is being taken for granted. I feel this way because I was also misled to think on the other contract I have I was going to get 30GB all time data plus 20GB night but it turned up I was only getting 20GB and only because I fought when I was only given 10GB all time data. I never got my written contract. I was referred to a number that was not being picked up till my airtime was finished. Why MTN cannot get the contract for me from their agent?