I wasn't. Had it been a 15-minute wait to talk while my food was getting cold, I would have walked out after a few minutes.
Here I was waiting for the burrito (the final item) anyway. I figured once I got my burrito, then I was actually waiting just for the refund, and at that point I would get more aggressive about demanding the manager come talk to me (though I had already asked for it earlier, as you saw from the story).
The 5 or so additional minutes I waited after the burrito came was about the max time I would have waited before just walking out and dealing with it later. However, this of course was inappropriate because they had known for 15+ minutes that I was waiting for this refund, and doing so literally took 30 seconds at most. That idiot manager just didn't feel like interrupting her burrito-making to help me.