This number is linked to LoanMart. LoanMart is a loan company where you finance your car through them by giving them the title of your vehicle. If they are trying to get a hold of you, it's most likely due to you being a referral from somewhat who got a loan. Hope this is helpful.
This "Law Investigator" approches with case # then goes on to ask last payment date and inquire how many payments are behind. Then once you've contacted 800LoanMart they go on to say they are in no way affilated to one another. I guess the goal is to bring outstanding account current and by using this scare tactic it sometime works out.