Insurer doesn't want to pay

In March a third party drove into me. Details were shared and I went to the police station to get an accident report. I shared the accident report with the third party, communication lines were open. The incident was then reported to my insurer (Discovery). My claim was processed where I had to pay an access fee of R5000 for my claim to be approved. That was done and my claim went through. The third party has a broker where I think he is insured by Old Mutual and according to the information I received is that old mutual is not willing to pay my insurance so that i can get my money back. Sheriffs have been sent out and they cant seem to find the third party, my question is why does old mutual not want to pay my insurance so that they can pay me. I did not ask for the third party to drive into me while standing in front of my gate to drive out and take my daughter to school.....I was stationery and driven into.....now that i need to be compensated there are issues and delays.....Why is that......I need this to be looked into and answers to be given to me as to why the third insurance/broker don't want to pay my insurance in order for me to be reimbursed....