I have an iPhone 6s that suffers from the now-notorious battery wear issue, where Apple throttles performance in response to batteries that don't hold their full designed charge anymore. I made an appointment for the new $29 battery replacement via Apple support chat. I showed up at the Apple store for my battery replacement appointment, and was told they had no batteries in stock and needed to order one. How does an otherwise impressive supply chain operation fail like this? They knew I was coming, they knew lots of people were coming (appointment required!) but now I have to wait until they call me to tell me the battery is in.

They did say they'd do it for free, which is nice.

/rant