The petrol attendant forgot to close the coolant tank that caused damage on my engine

The petrol attendant forgot to close the coolant tank that caused damage on my engine. It did lodge a complaint they told I must submit diagnostic report, quotation and book service if I have it. I send them on the 31 July 2026, they told me they will send it to their insurance. Still no feed back then I emailed their head office then they email back to me and some whose in change of Whittlesea Astron energy to respond on my ***. It's been three months without any tangible response with them. I'm stressed now because Renault will charge me for storage.