That is the procedure they follow. Just keep checking up with them after a week's time. Alternatively, you can go over to any Traffic Police office (Maroor) and check with them by giving them the car number. They will advise you if there is a penalty on the car on that particular date. If there is none, you can take a report from them and give it to the rent-a-car company and demand they unblock your credit card immediately. You can talk to the Captain at the Maroor office should you need help. They are very understanding, cooperative and helpful.