"How do I change it to a plus 2?"

This happened after my first message to everyone who didn't respond by the RSVP deadline which already irked me. This person replied, after seeing that the online form gave them a plus one, "How do I change it to a plus 2?" Not can I bring an extra person, not do you have space for one more, just straight to how do I change it. Um... YOU DON'T. This isn't Ticketmaster where you click the + button until you've selected your desired quantity. And btw I've only met you like twice, you're lucky you got a plus one. Of course I didn't say that, just kindly let them know we can't accommodate extras at the moment. But the sheer entitlement just made me need a quick vent.