@Paul8663
Im sorry to hear about your situation, I live in Nai Harn area also,
Airbnb customer service should have got back to you I agree,
I take you entered the property? was it self check in or did somebody meet you there?
How did you know you was at another villa?
It's likely that villa has been empty for a long time if the toilets were that bad the water is ground water but that not an excuse, I know what happens here.
When our properties are empty we always flush the toilets,
As of now have Airbnb got back to you? Now 4-15 pm,