courtesy car is been taken away and my claim is not finalised

I have claimed on the 25th of September 2017 and only given a courtesy car on the 13th of October 2017. Today is the 1st and the courtesy car is due back on the 5th, this insurance has not yet finalised my claim and they are saying I must return the car or else I will be liable for the cost. is this far? I was never part of the delay to finalise the claim, I have given them every document they needed on time, so now why must I pay for someone's bad service? But guess what, I never skip my premium and this is the service I am getting. How I'm I suppose to go to work now?