What action can be taken in such a scenario as per the UAE law?

Question: I am a garage owner. Six months ago, I received a car from someone for repair. The car was repaired within 20 days. I tried to contact the car owner for delivery, but the car owner did not respond. A week ago, he showed up.
Accordingly, I asked him to pay the car repair bill in addition to the parking costs, as it is stated in the car entry paper that the car owner must pay Dh100 for every day that the car is left after the repair is completed. But the car owner is refusing to pay the amount. He is also refusing to pay the cost of repair saying the amount is exaggerated.
What is the appropriate action to take against him?
Answer: The contract, as per Articles 125 & 246 of the UAE Civil Transactions Law, concerns an offer issued by one of the contracting parties with the acceptance made by another party. It can be implemented according to the provisions contained therein and in a manner consistent with the requirements of good faith.
Moreover, the author of any tort, even if not discerning, shall be bound to repair the prejudice and damages, under all circumstances, and they shall be assessed to cover the prejudice sustained with the lost profit provided it and shall include moral and material loses.
No one, as per Article (318) of the Civil Transactions Law, “is entitled without cause, to enrich himself to the detriment of another person, without just cause. If he does so, he is liable to restitute it."
Based on this and on your agreement in the car entry paper that the car owner must pay an amount of Dh100 per day after the repair is completed, you can file a civil case against the owner of the car to claim the repair charges, parking costs and other compensation for any losses you have suffered due to this.