Key question: Do you still have the old location? That is, is your account still active even if you're not using it? Does it have its own identity at gwt? Can you yourself (not the host) make an htaccess in the old location? If it's your own htaccess, it's hard to see how they could prevent you from redirecting.

What's your relationship with the inbound link providers? Will they take you at your word if you ask them to change the link?

In extreme circumstances there's the page-level redirect (the one where users twiddle their thumbs for three seconds and hope for the best while swearing at the site owner). Got a vague idea the arguments against this method run into multiple digits.