Although it may seem like you do not need to replace the windshield, it is not your car and therefore not your decision. Since the chip may lead to a crack, it is in the best interest to replace the windshield. You really should have checked the car for damage, especially the windshield. I feel for you, but you will likely lose out and have to pay or get sent to collections or waste countless hours of your time dealing with this. Find out if they have taken the car to the shop yet, likely they just rerented it without fixing it, and if that is the case, ask for the area manager's info. Go from there.