Security interest from bank.
I have a campground in NJ and had a customer who owed me $2000 for camping so we did not allow him to remove his trailer last October. Now the Credit Union which handles the customers trailer wants to repossess the trailer and we denied them access until we are paid the $2000. They have since written to us through a lawyer and offered $750 to quickly dispose of the matter and retrieve their trailer however they said they have a "superior security interest" in the trailer and that we cannot legally withhold the trailer from them siting NJSA 39:10A-20. While I have heard you cannot hold the trailer for Towing and storage charges we are holding the trailer for services rendered.
My question is: Does a credit company "always " have a "superior security interest" or are their circumstances where they don't and must pay the charges to retrieve the trailer.