If someone else used your details, and the site blocked you; then they would have been blocking the IP they traced at the last moment before they blocked you. So its unlikely that somebody using your details could have made them block you and not the person usnig them.
Unless this is a problem with Login Details?
Best idea is what rakedog said; e-mail the Admin and tell them about the problem.
A Knight is sworn to Honour. His heart knows only Virtue. His blade defends the helpless. His might upholds the Weak. His word speaks only truth. His wrath undoes the Wicked.