As long as the at-fault party provide/release the details of the policy, they have complied. You are claiming via your own insurance, you are contractually obliged to pay the excess, you agreed to pay the £600 excess at the inception of the policy. All of these things you agreed to prior to the accident. Even though it is not your fault, this is the contract you agreed to. If you do not want to pay your excess, use a claims management company. The alternative is to have to wait until liability has been admitted. The other party has the right to investigate prior to admitting liability. You could contact the police and advise the other party has refused to provide his name and insurance details. Speak to the transport manager and request from them or you will litigate against the company rather than the insurer. This should push them to provide the information.