MTN makes it impossible to switch from contract to prepaid and forces upgrade on me

One of my contracts is expiring this month. All I need MTN to do is switch that contract to prepaid. A store visit and multiple calls later, still nothing has been done. My 4th call to them was over 20 min long and it's still not done.

Every consultant is ready to upgrade but nobody is willing to switch my number ending 2607 to prepaid. After making all this effort to cancel, I'm still getting calls to Upgrade but that consultant can't process the prepaid request and he can't transfer me to someone who can.

What is the point of taking a 24 month contract if I must call after the 24th month to switch to prepaid, If request to cancel the contract in this month (which is the 24th month), then I incur a cancellation fee.

I AM NOT CANCELLING MY CONTRACT, I WANT IT TO END ON THE STIPULATED DATE! I DON'T WANT AN UPGRADE