I am also hitting a wall with Etihad.
After arrival from AUH at DUS, two of our Rimowa suitcases were heavily damaged. The bagage office refused to draw a DPR and told us to contact EY directly, so I sent my claim to the Guest Gold customer service who forwarded it to the baggagedepartment. I received a response that Etihad would not take liability for the damage. I replied that Etihad was liable for damage to baggage under the Montreal Convention and that I would claim for the full repair costs, as determined by an authorized repairshop. They still dismiss responsibility and refuse to pay.
Where can I escalate this matter?