Vestel Air Conditioner Installation Error

I purchased an air conditioner from a Vestel authorized store about 2 years ago. When the technician from the authorized service came to install it, he accidentally broke the drainage pipe inside the wall while drilling. We only found out about this when heavy rain on May 23, 2024, caused water to flood into our downstairs neighbor's apartment. When we complained to Vestel, the service manager called me, refusing to acknowledge the incident by saying it happened 2 years ago. He even engaged in an argument, trying to avoid responsibility. It's absurd that I'm being questioned by a Vestel representative when the external drainage pipe of the entire building suffered major damage due to the mistake of an incompetent installation worker. The repair requires hiring a crane and a plumber to replace the entire drainage pipe from the outside of the building, turning into a significant problem. This negligent employee, who caused damage equal to the price of the air conditioner, failed to inform us about the mistake in a timely manner. Now, I'm dealing with separate parties including the building residents, Vestel manager, complaints center, and the building's insurance company, just to resolve the issue. I demand an urgent repair of the mistake to prevent further disasters. Depending on the response and approach to solving this issue, I will continue to seek justice from all relevant parties.