The bond that you pay upfront when you hire your rental car is refunded to you once the car has been inspected. From there it will take approximately 5-10 days for the money to be deposited back into your original account. If there are any problems with the car, you will be charged accordingly, depending on what the issue may be. If any damage has occurred to the car and you aren't insured, the cost of the damage will be taken out of the account that the bond was originally taken from. If you are insured and damage has occurred, get in touch with the insurance provider and tell them what has happened and what the issues are. If there are no issues are present with the car, all you need to do is wait 5-10 business days for a full refund on your bond.
Over busy periods such as Christmas and Easter your bond refund may take the whole 10 days, if it has exceed 10 days, make sure to contact the car supplier. In quiet periods, you may receive your refund in just a few days. It all depends on the how busy they are and if there are any issues with the vehicle.
Read more about everything you need to know about returning a rental car.