Auto Insurance Claims: Suing me, 3rd party insurer not working through my insurance company, letter in the mail, insurance carrier

Question
Dear Mr. Hixenbaugh,
My son was involved in an accident over a year ago.  He was cited for failing to yield on a left turn.  Both his car and the 3rd party's car were totaled.  My insurance company believes that some fault lies with both drivers and had made a 50-50 offer to the 3rd party's insurance carrier.  The 3rd party's insurance carrier has been unresponsive for the past year and has not responded to many attempts at contact from my insurance carrier.  Out of nowhere, I get a letter in the mail from some attorney's office attempting to collect 100% of the damages from me, effectively cutting my insurance carrier out of the picture.  I immediately notified my insurance carrier and they have been great and have told me that they will handle everything.  My question is, isn't there some obligation for the insurance companies to work together?  I live in the state of Illinois and my insurance carrier states that if both insurance companies do not agree then they need to settle in arbitration.  Is what the 3rd party's carrier doing common? legal?

Answer
Hi Jeff,

Yes this is normal. In reality you are the one that owes the money for the damage you caused. You have insurance to cover those things that you owe. When ther is a dispute as to how much is owed or who is at fault or for what percentage, sometimes they will try to sue you. But don't worry, just be sure to turn over anything you receive in the mail to your insurance company and they will handle it. If you actually are sued your insurance company will provide you with a defense attorney.

I hope this helps
Richard Hixnebaugh