Customers battling Boomerang Systems Inc. over its robotic parking valet system are threatening to derail the company's chapter 11 restructuring, Dow Jones Daily Bankruptcy Review reported today. The owners of parking garages in Illinois and Kansas that were supposed to feature Boomerang's RoboticValet system on Monday filed papers urging a bankruptcy judge to either convert the company's chapter 11 restructuring to a liquidation or to hand control of the company to a trustee. "There is no chance the debtors rehabilitate as a viable entity while providing an equitable return to creditors," the garage owners said in the filing.