My understanding is that if I fly from point A to point B (either non stop or with a connection), and use a regional certificate, I use one certificate for the trip. I just redeemed for an upgrade today and was told otherwise: i.e. one regional upgrade certificate per segment (so 2 certificates in my case, for a RSW-ATL-SFO one way trip).

What is the real story? I've been only 'charged' for one certificate for previous usage (and all involved connections, every last one of them), so is this agent incorrect, or am I?

Thanks!