Advice for how to go forward with no communication from artist

[Miorjah]

 Hey! I commissioned an artist in late september, I had commissioned them 2 times before with no problem with a 25-35 day turnaround both times. 

on october 25th, I recieved an email apologizing for the delay and It would take longer than expected. No big deal, as they seem to be chronically ill and I can relate.

However... that was the last communication i received, and that was "it might take 2 more weeks".

I've emailed them 6 times now, and they've opened for commissions 3 more times, and have stated on each opening that we will get our art soon. 

The last promise was that I'd receive my piece by early January on a public Furaffinity journal. I also found out one of my friends has been waiting on a commission since august.

I'm torn on how to move forward, at this point, I sold the character in the artwork to another friend (who is not interested in the artwork as far as I'm aware),  and am considering chargeback as It's growing close to paypal's "chargeback by" date. But I'm also concerned of putting the artist In a bad spot. I don't know if trying to shout on their FA or @ on twitter is an appropriate message to take? as they're mostly unactive on both platforms besides occasional commission announcements.

[Bornes]

Issue an ultimatum. The guide is in my forum signature and the resources section.