Problem with user registration process on membership plugin

When the registration form is completed (http://www.bizbritain.org/register.html?action=registeruser&subscription=1), instead of being re-directed to the confirmation page, the user is given the message:

“Sign up for Membership

You currently have a subscription for the Membership subscription. If you wish to sign up a different subscription then you can do below.”

Then below there is just a blank space below, with no option to do anything else. Obviously this makes no sense, one would expect that at this point the user would be re-directed to the confirmation page?

I’ve tried absolutely everything I can think of and still cannot resolve the issue.

Thanks,

Matt