Error whenever I try to login with my facebook, please help anyone

[Cotterillx]

I've tried multiple times over the past few months to login with Facebook but whenever I try to login I get the error code shown in the screenshot. I can't remember ever getting into it on my facebook but it says my username is maia90, I would never set this as my username but I don't think my account has been hacked because my facebook account is still working on everything else. I've spoken to support on live chat but they have said my persona ID isn't linked to an account so I can't login to save data and my account that is apparently linked to my fb. Can someone please make some sense out of this, thanks.