2009 Mazda 6 wire harness question?

[life's a beach]

I was involved in a wreck about a month and a half ago. I got hit on the drivers side, i was basically t-boned. I was going to get my car today but all the lights on my dash were lit up. So the collision people took it to a mazda dealership. The dealership said my car needs a new wire harness. It has been stretched. How long does it usually take to repair this? Is it a major ordeal to get this repaired?

Thanks so much!