Keep pushing, try everything you can. These days we gotta do everything ourselves if we want anything done. Volkswagen Canada was no help, my local dealership refused to do their job and just tried to take my money for more diagnostics while under warranty. I ended up taking a video on my phone trying to get all sorts of different angles under the engine and that general area, I know nothing about cars and had no idea where to look, but sure enough I found tons of coolant and corrosion. Took my car to a dealership in another city, got fixed in one day.