I'm beginning to think this is a common occurrence in VAG cars in general and the mechanics just accept it. The mechanic behind this YouTube channel works for Audi and every single Audi that rolls into the shop has low coolant. Until VAG redesigns their coolant and cooling system or an aftermarket upgrade comes along, this is something we'll have to live with for the rest of our ownership. Yeah if you go from max to min in 2000km, then that's an issue. But if it takes you 20k km, then it's probably considered acceptable.The thermostat housing leak passes a pressure test. It leaks while the car is driven and the coolant is up to temperature. Tell them to visually inspect it. Every dealer is certainly aware of the thermostat housing leak and should know better than to pressure test it.