S4 b6 manual transmission reverse switch wiring

So based in U.K, just bought a convertible s4 B6 manual as a project. Reverse lights dont work but bulbs are good, as is fuse. The switch on the gearbox is broken, as in there is no wire to it. New switch is ordered but cannot find the wire that plugs into it. I have acces to lifts so have been under but nothing seems to be dangling free or unplugged. Looked at tons of diagrams which show the switch, but not the wiring route or location. Need help please if anyone knows it would be much appreciated. Thanks in advance.