Hi Tom,
i am literally having the same issue as you, I have taken the whole interior out and couldn’t find the leak anywhere - started on both passenger side footwells, completely soaked, and then obviously made it’s way over to the drivers side footwells as it’s getting soaked up from the carpet - hopefully we can find the issue on this post just wanted to know that I have the exact same issue with my Audi a1 and have done for months - Joe