filesharingcenter.com I believe is also mentioned on here (p.5 I think) Known Scam Sites (click on link)

That 'sign-in' scenario seems to be the same on all their links on that page. Check the contact one & see if you can actually send a message after entering your member name, etc. (except for any credit card bizo)

Since you know it's filesharingcenter.com then check their other links from this site & look for contact details there (look for them on the link above.) Sorry ... normally I'd research this myself for you.