This is only the 4th post I have read on this site, and the responses, which always seem to criticize the letter writer, are already getting tiresome. The cashier should have asked for the perks #, that's part of her job. Rather than going on the offense, she should have apologized.

I also think the previous low quality of service just got to be too much for this particular customer--but characterizing the cashier as a "moron" and asking for her to be fired is a bit over the top.