Don't want to take sides or anything but as some one who worked in retail for a few years...

Customers that request stores to stay open after trading hours place both themselves and the store at risk. Also sales people have lives and would like to attend to them. I lost count at the times I went home an hour later because, people where late shoppers.

On the other hand...

I can emphasise with Flex's disgust in driving to a empty store, I would be miffed too.
However would it not have been better to arrange the pick up when you did have time? If I was going to run late on a pick up I would forgo the item until a time that is convenient for myself.