645 V8 Engine replacement ! Dear God !

Worst possible news..my 2005 BMW 645 is currently in with the main dealer. It cut out recently during the bad weather as I drove through what genuinely was fairly low and inoffensive standing water. There was some splashback over the wheels and the car restarted but went into safe mode so I tentatively drove home and hoped it was just a sensor issue from the splashed water and that the few minutes drive would dry it out.

The next morning I started the car only for the engine light to still be on and the engine was tapping loudly. I took it to Copper BMW this morning. They are still looking at it but they have given me a preliminary "heads up" that the air filter was wet and it looks like possible bent conrods as water has got into the engine....
They need to do further diagnostics but are stating the knock on effect of water in the engine means a possible bill for a full engine replacement, circa £12,000...
Has anybody at all got any contacts at all for a respected source for a reconditioned engine as I fear this is the only possible avenue.
Great news to be given at Xmas and New Year eh?