What do I do about a son that never registered, insured or titled my old car and lives across the country?

It's been over 2 years since I've moved across the US. I sold my car to my son prior to moving but he never turned in the license plates, registered or insured the car. I did insure the car for 2 years to protect myself and allow him to "get back on his feet" after he lost his job and his home. I cannot afford to fly back to that suburban city, (and don't know where my son is living) especially just to remove the plates and turn them in to DMV. The car is 7 years old. I can't legally take the car because I signed the Title over. Is there a "service" that can remove the plates for me?