You said that the bitcoin will be sent back? I don't think it was a scam if it would be back to the sender. Maybe it's just a system bug or a faulty program on the website.
Maybe it's a new verison of the scam script that tells you your payment has failed they will return your payment ...but do another one!
So they can scam you more.Op, you should add the first part of the scam:
A newbie account claims he has have found a way to hack some website so you can get free cards or whatever
You need to install tampermonkey and install a script (encrypted) from a pastebin page.
Whenever you will go to that website, every address your browser sees will be changed to the address of the scammers.
But it's an old scam, not really new and it does need the user to be able to install a script, which weed out 99% of the ones foolish enough to be tricked by this, fortunately.