Loose headlight wiring harness
 

My drivers side low beam constantly is going out. I took it to theveryone dealership and they said it was a loose wiring harness for my drivers side light. They also wanted $135 to fix it but I think that's outrageous. Can someone point me to a guide to replace the wiring harness in a 01 subaru imprezza outback and possibly the part to replace it? Thanks