not taken it to the garage but i asked Audi yesterday and he said it may not be coming in from the corner area it may be along the front somewhere, and that is is difficult to find and may be quite expensive to fix!!
both on the right and left hand sides where the roof joins the car through the plastic trim i have cleaned out the tubes and put in grease it is better but not completely cured.
I have a leak in my roof and have been told you can adjust and tighten the roof slightly forward to get a better seal
has anyone tried this or have a leak that they have managed to repair