Being denied like-for-like hire car

hi guys,
i was involved in a 3 car shunt, where my car was stationary at a round about.

taken 14 days so far but the accident company dealing with my claim have got me booked in with a garage to be repaired as estimate as gone through and been approved.

Now they are saying since the other two parties are blaming each other and not accepting liability, they are unable to give me a like-for-like courtesy car.
Where do i stand with this?