Agent x, excellent - I'm much obliged. Hope this hasn't spoiled your Sunday, digging around in the manuals, but it's helped a lot.
Hopefully the post will help others. A wider awareness of what airlines are expected to do will help everyone understand what can be done. I'll take it up with the ticket agent tomorrow.
it's a reflection of the quality of the forums, too - there's a lot of expertise on these boards, a credit to those who take the time. Thanks again for a useful post.
regards Westerman