I claimed from them as a third party but they told me that they will not pay me or fix my car because their client was wrong and forfeited the claim

I claimed from them as a third party but they told me that they will not pay me or fix my car because their client was wrong and forfeited the claim.They said he won't be covered because he was driving in a high speed..Their client hit my car from the back..My number is ***..The accident happened on the 27/08/2023..