Blacklisting Services Gone Wrong

I called the call centre this morning after my phone got lost to blacklist it. I was told that the IME number cannot be picked up and that I should go to a MTN store. I went to the MTN store at Rosebank with my ID and proof of purchase and filled in a form. I was told that I would be contacted as soon as it is done. I called the call centre now and they don't know anything about filling in a form. I made a call this morning from the number in question but they not picking this up. This is frustrating as i'm not sure whose telling me the truth or will this be sorted. the number that gost lost with the cellphone is prepaid.