Focus rear lights and dash keep blowing light switch fuse?

Ford Focus '99 rear lights and dash gone!

Whenever I switch my lights on the 'light switch' fuse (32) blows. This means the rear lights and dash lights don't work. Park lights work and front lights are working. I have checked the ulbs and connections on the rear lights. I even changed the light switch with a spare from ebay but no joy. My only thoughts is about the wiring, one possible source of problem is driver mirror got knocked recently and the cover fell off the front - haven't been quick in fixing and been open for couple of months. Could the mirror electrics be cause of my problem or should i just take to garage?

Help