I suggest that you your next step is to write a letter to the owner. The employee may not have mentioned it to the owner. You can usually look up the owner information online at the property appraiser website. It would be helpful if you have an estimate for the cost of the repair to your vehicle when you write to the owner as well.
The owner is liable if you can prove that the damage happened at the car wash and that will be difficult. Prepare a letter of notice and mail it to the car wash "attention: owner". Or, visit the car wash and ask to see the owner. Take good pictures of the damage and take them with you. The car wash, most likely, has insurance for this type of occurance. Ask him to notify his insurance company; if he doesn't, he may forfeit his right to coverage under Michigan law. Good luck.
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