IEM Number help

Hi there, here my story in short.

My phone got stolen, I got the phone blocked and the sim-swop the next day. When the simcard got active I noticed that most of my airtime was missing. MTN call centre confirm that the airtime was transferred to another number shortly after it got stolen.:erm:

-I don't have the IEM number - phone is 5 years old.
-MTN refuse to given me the number the airtime was transferred to without a case number.
-SAPS refuse to help me without the IEM number.

Any advice here? I'm more interested in catching the person than getting my phone back.