MTN Cancelation

My 24 Months contract ended on 26th of January at MTN I've phoned in on the 28th of February to make my number prepaid. Up till now after a telephone call 60 minutes long today. I am still on contract after they have told me today that my number is prepaid now but it is not. I've spoke to 5 different people today and still my problem is not resolved. I also visit the MTN shop this morning and nobody could assist.