Claims that take forever to be paid oht

So we've been waiting for feedback regarding a claim. Their insured gets to take his time to pay his excess fee while we wait. Surely it's not our problem and we should be paid out so that we can carry on with our lives. Our car which has been damaged by their insured since January is now getting rusted due to this long wait which is unacceptable. Been sent from one person to another and I am rather ****ed off right now