From my experience, they will only fully write a car off if the amount of damage exceeds the current market value of the car. So if there is $5000 worth of damage and the car is worth $20000, they will repair the car.

I think it is crazy the amount of time you have to wait for repairs though. Are you entitled to a hire car paid for by your insurance during that time? If so, tell them you'll be applying for that and see if that helps them speed things up with your claim.

Good luck