C A S Power Marine

I purchased a used 23-​foot waterski tow boat last fall. I paid CAS Marine to inspect it then service it after I purchased it. I used it for a short while then brought it to them to service and winterize it. When I launched it last Saturday it began to slowly sink.
I took it back to them and they found a split hose in the cooling system and emailed me an invoice for replacing it. When I asked if wasn’t the point of winterizing to avoid exactly this problem, the response was that winterizing doesn’t help old hoses. When I pointed out that eoven I could tell an old hose that needed replacement by squeezing it and I had paid them to inspect the boat and made every repair they recommended, they still refused to accept responsibility, at one point saying they only had three or four customers with tow boats as if that absolved them from their incompetence.
I am no longer a customer.