Software that isn't user friendly, and you can't contact a human for help.
I ran into this today. I was trying to make an online reservation in the economy parking at a nearby airport.
It didn't say you had to set up an account, but there was a guest option so I thought I could just go with that.
Anyway, when I entered all my information, it said it couldn't process my credit card. I knew nothing was wrong with that card, but I tried another card anyway and got the same response.
I called the airport and ultimately someone who worked for the company that handled the online reservations. They weren't much help, just told me to keep trying online. They did say maybe the economy lot was filled up.
Finally I was able to make a reservation in a lot that was a bit more expensive than the economy parking. Had I received the message that the economy parking wasn't available earlier, it would have spared me a lot of aggravation.
IME, there's starting to be more of that. No help, no backup, and web pages that aren't user friendly.
Ah, the joys of technology without support.