According to companies house Firevision are in liquidation.
Apparently the firevision web site was down in december although it is back up and running again and I have read on other forums that they are appealing against the liquidation.
I have three domains registered with them and have tried to move the TAG away without luck.
I've spoken to Nominet and they confirm that they are accepting automaton instructions from Firevision, so its looks as if TAG changes from their site are a manual process and no one is there to do them. You can get Nominet to change the TAG for a fee of £15-00 and if you have business names with Firevision this may be the best route.
I'd be interested to know if anyone else has had any luck moving the ISPTAG from Firevision.