I started at the web site today to change an award flight to the same itin, but a day later. Web site told me that it was available for an extra 8,000 miles - okay. But then it wouldn't book it for me. So I called and got the try chat or we'll call you back.
I tried chat - first to the bot that sent me to the app to try to do what I'd tried to do on my own. Then to a chat agent Axxxa. I explained what I was trying to do; she confirmed that I only wanted to change the outbound and said I'll work on it. She got me exactly what I aske for and for no add-on. So, just like the phone, there are agents who know what they are doing and agents who don't - I got a good one today.
My only issue with using the chat is that it probably took longer than it would have with an agent.