What a mess!
For future reference, it is the seller's responsibility to make sure that the title
of the vehicle passes to the buyer upon sale of the vehicle.
The tow company had to send you legal notice of their claim to junk out the truck. They are only legally entitled to do this after they obtained a transfer of title through the storage yard lien statute in Illinois. To confirm this happened, you should check to see who has title to the vehicle at present by checking the VIN with the Secretary of State
Because you never made sure that the title was transferred, the car remained legally yours. Thus, you would be liable to any third-party, such as a storage yard or tow truck company, that has performed services in connection with the truck.
That being said, the tow truck company could have messed up the "junking" of the truck by failing to send proper notices regarding their intent to take title to the car. You are also entitled to dispute the amount that the debt collector is seeking from you based on the fact that the debt collector does not have proper documentation of the debt. That documentation would include any credit which is due to you for the money that the tow truck company got by "junking' the truck.
You should immediately dispute the claim on your credit report. This is one way to start the ball rolling. Also, dispute the claim with the billing agency and demand the documentation.
In the end, they may have the proper documentation and may have sent the proper notices. If so, then you would be liable to pay the tow and storage bill due.
Payment of the collections at the amount demanded should clear your credit report.
In the end, it is the girl's fault. Of course, you can sue her for the damages that have resulted.
Please let me know if you need further information.
Best of Luck,
Zachary D. Norris