How long do customers wait for replacement parts?

Is there a guideline for how long customers need to wait for parts? I was rear ended 20 minutes after I picked up my new Renault Megane GT Line from the dealer in May this year. It's now nearly August and Renault still doesn't have the parts here for the panel shop. Surely there must be some sort of consumer protection regarding parts being available for customers so we can get our cars back in a timely manner.