Hubby heard from head mechanic yesterday. He said they pulled 3 gallons of water out. We added some type of additives to take care of whatever was remaining.
He wouldn't come out and say it came from the fuel but he said in his professional opinion, the engines would not have run with that amount of water in the fuel. He said if they were running and then they were not, whatever happened in the interim is where the water came from. And the only thing that happened in the interim was getting fuel.
He is separating the water removal part of the work and putting that on a separate invoice and including the details and his opinion. The cost was just under $400.
The rest of the work we were already having done which was just a general servicing/tune up.
At the end of the day it could have been a lot worse and I'm just happy our engines and generator are back up and running.
It's a win and actually one of the advantages of gas that made it easier to clean and proceed. Now, you still need to be on the lookout as to causes of water getting in. Don't assume it was the fuel.
As to arguing with the marina, you have no argument really, even as much as you believe. They say "no" and even the mechanic you paid will not point the finger at them. Without an expert statement on the record, you really have nothing but a good lesson and a quickly fixed problem and time to get boating. Plus a testimony for towing membership.