Certificates of Revalidation may only be signed by Examiners. So yes, the FI's error needs to be corrected before the end of 30 Jun 2009.
Why on earth did an FI who is not an Examiner think he was empowered to sign Rating revlidations in pilot licences?
You should not be expected to pay for an Examiner to sign your Certificate of Revalidation - name and shame if you are!