For the record, I'm not really the biggest fan of their burgers in general. But the customer service is what really ruins it for me.
If you wait in line for 30 minutes I would expect that someone would come outside and let you know their credit card machine isn't working. That way you're not stuck in line for another 30 minutes while you wait for everyone else to get food expect you.
Also, make sure you ask them to try your card at the window, it will work 10 times out of 10. The kid at the window will make sure to tell you, with attitude, that "if your card doesn't go through it won't mean you get free food." My card had worked every time. They just don't want to make food past 1:00, even though they're open till 1:30 Friday and Saturday. Seriously. If you're going to not accept credit/debit cards past 12:30 then maybe put a sign up, and you'll need to make a few more exits in your drive through so people don't have to wait for 1 hour.