deregistering a vehicle proving to be complicated

On the 16th of October I phoned Cartrack to deregister one of vehicles that had been sold. I was told that because we are a business I would have to complete forms for this to happen and I was to send an email to them requesting the forms. I did this but heard nothing. Ive since sent the email again. Contacted them on their website, but no-one is getting back to me. Now this vehicle is no longer in our possession and I don't know if this is going to be a problem. It would have been really nice if they could have emailed me the forms shortly after the email was sent.