cheers od, doomie and chinners - i was livid when i wrote that. the ticket office didn't seem in the slightest bit interested that their system was broken, and could potentially cost me a few hundred quid.
anyway, i emailed the norwich ticket office, and got a reply in 3 minutes saying that they'd make sure we got in and sat together, somehow, but it might have to be in the home end (even though that's sold out too). not really what i want but top marks for customer service.