After their initial ban from FA and the large rant they appear to have made about it on Twitter I didn't think they'd return. When they did I figured now would be a good time to post about their behavior and taking of people's money.
There's not going to be any resolution to this unfortunately though, I sent them a message of the beware, told them I don't want any of their art, and even mentioned that I don't really expect a refund as I've talked to others and they do not give them out despite having no TOS about it. They gave me this response below and blocked me. I can try to communicate to them through other channels but I feel that borders on harassment territory and ultimately they'd just block me.
I'm chalking this up to a learning experience as a commissioner that you should have a reasonable expectation of what artists meet and if they fail that immediately do not be afraid to call them out. If they just drag you along and get defensive on demanding a refund you need to deliver an ultimatum and if paid via a third party site file a dispute in the time frame you have to do so.