Your customer doesn't care how busy you are. It’s not their problem someone’s transmission went out, or that another will be there in 5 minutes despite that fact that you haven’t even gotten the car washed yet, nor the fact that yesterday’s “lick” (a.k.a. a customer that paid you a healthy commission) now wants to return the car. Customers aren't ignorant to the fact that you are busy helping others-they just don’t want you to be too busy to help them. 

You see, not long ago, it was you who sold them on the gadgets and prestige of owning their new vehicle. It was you who convinced them to stay when they wanted to keep shopping. You were the one who promised that you would be there for them anytime they needed you…I guess today doesn’t qualify for anytime. 

Customers get angry because they feel they’ve been betrayed. You were the one who whispered blissful promises prompting them to make a decision to stay, yet you failed to tell them that those promises end at midnight tonight.

It is true, your customers want the most for the least-they want the most service for the least risk. That’s why they’ve contractually invested their trust in you.  Sure, it’s easy for you to just throw your hands up and walk away, but true professionals, in good times and bad, commit both the time and effort to make the marriage work.