MTN blocked my number

Ive had the same number with MTN for years now. On the 16/06/2020 my contract expired and I decided to cancel it since I give out a ridiculous amount of money on extra data plus the monthly installment. I called in, waited for 30 minutes then I finally spoke to someone. I told the person I want to cancel and he asked me all the questions including what number it is I'm using. He then proceeded to offer me another contract which was cheaper (just a data contract) which I refused. He then told me I'd be switched over to prepaid and I'd lose all the data and airtime I had. Up until this point it was smooth sailing. I got the text saying that the contract will be canceled on 16/06/2020 then I got another text the next day saying it will be canceled on 18/06/2020 and I will be billed according and the first text also said that an agent will contact me. On Friday 19/06/2020 I realised my number wasn't working, I can make calls but when someone calls me it says that the number does not exist. I have been trying to call MTN but it's impossible to speak to an actual person if you are not in contract, that option isn't available to you. I've sent a few emails and my query just gets moved back and forth. I am lost, I don't know what to do. I use this number for work and since it's been my number for years, all my contacts use it. I don't know how to get hold of mtn and how to get my problem sorted since it is just shoved around from 1 department to the next