It's not in your insurance company's interest or the other party's interest to defend. If it goes 50/50, then both insurance policies will be affected, both will lose any NCB, both will have increased premiums and both insurers will profit. Advise your insurer that you are in no way liable for the incident and hold the other party fully responsible. Advise your insurer that you insist both your vehicle and the other party's vehicles are inspected and the damage compared. This is called a "causation" report. Tell your insurer that you wish they take this to court to defend your position, as you know the third party had no available witness, they will be found in contempt of court. Also advise your insurer that you "may" pursue a personal injury claim for emotional distress and as such they should not prejudice your legal position or entitlement by admitting liability. I am not suggesting you make a claim for an injury you do not have, but it is important the insurer is aware they can prejudice your lawful entitlement. Advise your insurer that should they admit liability, that you will sue them for any financial loss sustained for breach of contract. Whether you do or not is a different matter. Also raise a complaint and complain to the financial ombudsman as well.