I think we can all agree that the artist should have replied to the first two notes, however the passive-aggressive from the customer when the artist finally replies, followed by overt hostility is alarming. I know that when I'm sick I have a shorter fuse and a I'm less likely to censor my thoughts than normal, so I can understand the artist getting cranky after that.

While I agree that FA journals aren't ideal methods for contacting clients, I'd check them if I thought the artist was running off with my money, and I find it weird that OP didn't. IMHO it's not strange that they're active on their account but not checking/replying to notes when they're sick. I don't check work emails but I fluff about on the tablet when I'm crook. Same difference, really.

Bottom line, the artist should have maintained better communication, but I don't think the commissioner needed to be so cold and uncaring. There were a lot of sentences that could have been phrased more neutrally.