Sorry to hear of the incident.
Unfortunately, this is how the claims procedure works with every insurance company.
Usually, whether fault or non-fault, you pay your excess (as some third parties may be uninsured, etc) & then get it back once it's all settled.
Your issue is the length of time it is taking. This happens because the third party refuse to accept liablilty and try & pin the blame on you though it may be blatantly obvious what happened.
Therefore, there then has to be a lengthy legal battle to prove the other person's fault. Once done, you get your excess back plus any out of pocket expenses you may have.
My friend had a claim & it took 3 years to sort but it should be much quicker in your case.
