MTN refusal to move account to prepaid

Good day,

I’m a contract customer of MTN. I called MTN today to cancel my contract due to its term over being and was told that I would have to wait 30 days for the contract to be cancelled. In the previous year I cancelled another contract a month before and was told tht there was no waiting period for contract cancellation and that this takes a few hours to be migrated to prepaid. I have followed what they had previously advised and now I’m met with this. When I took up this contract, this waiting period was never mentioned. Please help.