I try to be reasonable; I'm in a form of customer service, so I know what it's like.
However, when it comes my turn to be waited on, I consider my issue every bit as important as anyone else's,
and if they don't have time to deal with it they need to correct their shortcomings.
I have been treated exceptionally well at the NAPA store I frequent. It is at the state warehouse.
I have also walked out, with some others, when it didn't look like I would get waited on in a reasonable time.
To be fair, every other store I go to sometimes has the same problems.