I have a A6 2.5 tdi avant sport quattro, 2000 vintage, it has air suspension on the rear, my near side drops after a couple of hours, i have found the air bag leaking slowly with soapy water. can any one advise on whether the A6 all road air bag would fit, it looks the same in the manual but it has a different part number. failing this does anyone know a place to get a reasonably priced replacement or even a fix.