Damage to the vehicle caused by defective drainage channel

We live in a multi-family house with 7 apartments. Together with the neighboring house (5 apartments) we share an underground car park with a total of 12 parking spaces. The apartments are condominiums, which are partly self-used by the owners or are rented. We are apartment tenants. The WEG is represented by a house administration, there is a liability insurance for the WEG. From the underground car park a ramp leads straight and with even inclination to the At the top of the ramp there is an ACO Drain drainage channel. My wife left the underground garage with her VW Polo a few weeks ago. She drove at normal speed. When driving the drainage channel, the edge of the channel broke, the cover grate was lifted and hurled with great force against the underbody of the Polo. In doing so, the diesel fuel cooler was severely damaged, but is fortunately still dense. The damage was reported to WEG’s liability insurance company. The insurer then sent his registration form with the request for completion. This sheet was filled out and returned 2 days later. Confirmation of receipt by e-mail came immediately. As a result, no response came for 4 weeks. After a friendly request for the processing status we had the letter in the mail after 2 days with the words ” … a fault of our insured person is not We cannot offer compensation …” and “… but you can report the damage to your car insurance so that it regulates and checks whether it takes regress with us as a liability insurer …”. For us it is clear that the HP of the WEG has to afford. Nice attempt that we should report it to the UK. This only does work and trouble, because 300 Euro SB and just over 300 Euro damage. There our car insurer will definitely hang in there. What now? Again a compensation and we can not offer compensation …” and “… sharper letter to the insurance company with time limit setting and indication that the matter will be handed over to the lawyer if no answer or cover is given? Traffic law protection without SB would be available.