I was recently hired on an hourly contract on Upwork by a client. I completed the initial job and then the client offered more work, which I accepted, but then the client kept changing the job, putting pressure on to finish immediately but then constantly adding new requirements, giving very vague instructions and asking for countless revisions. I finished up the jobs I was doing for them and billed them for the week, already having decided that I didn't want to do any more work for them.
A few days after I submitted my hours, the clients account was suspended. I tried to make contact but no reply. I contacted Upwork but they said that because the hours were untracked, there was nothing they could do.
Finally, yesterday after the review period expired, the payment was declined. Again I messaged the client and got no reply, even though they had been constant in their responses during the work. From what I could see, they hadn't been online on Upwork in a week. So, I simply messaged the client via facebook, explaining that I would be taking legal action if I didn't get paid.
Lo and behold, I got a fast answer to that and have now been paid, along with a number of excuses. Apparently there was trouble with their bank which is now sorted and their Upwork account is now unsuspended. The client is fairly snotty at my threat of legal action. Obviously, I will not be working with them again, but did overreact in threatening legal action? I don't think so. I think it was very unprofessional of them to leave me in the dark, all it would have taken was a simple message from them explaining the situation in the first place.
I have a couple of different freelancers via peopleperhour.com mentioning that their accounts have been suspended. They have generally tried to find me outside but have generally only been able to, as I have given them my email for when I cannot easily login into the site and should they have queries.
So I think it might happen every now and again. The issue with freelance sites is that that they try to keep your details from each other, to stop you going outside their commission model. So maybe they didn't know how to contact you.
I guess in retrospect it might have been good to use the first message on FB to ask why you haven't been paid and then move to the threats. However, they aren't being very empathetic, you did the work and then they disappeared, no wonder you are annoyed.
They sound difficult to be honest, so not sure you have lost much there. I'd chalk it up to experience.