Complain to car hire company
Always complain to your car hire company in the first instance. You can do this verbally or in writing but make sure you keep a clear record of your complaint.
Give the car hire company a reasonable time to address your complaint and to rectify the situation, say 14 days.
If your complaint has not been resolved, you can then turn to one of a handful of organisations who have codes of conduct for members and aim to resolve disputes with customers.
2 Escalate your complaint