No, the rule has always been if it is refundable, the ticket remains refundable. The one time that I did call to let CO know that I would not make a flight, the agent told me she could not do anything with the ticket until the gate agent listed me as a no show and then she would be able to process the refund.

If CO does has the new rule, then I'll buy my full fare tickets on another airlines that allows for the flexibility that comes with the price. I have never had a problem in the past or with DL, US, NW, or WN. FL does require you to cancel an hour prior to departure.

I too have never heard of such a rule, at least not with a legacy carrier. The ticket becomes "used" when you board the flight, not when you check in.

And if you de-plane they can un-board you and the ticket is still not used.

Regarding the original agent not knowing the special rules that apply to refundable tickets (or rather, the notion that the new "special rules" apply to all tickets EXCEPT refundable tickets) does not surprise me. They probably see so few of them, and most of them that are purchased are perhaps purchased through corporate travel agencies, that they very rarely see your situation.

From time to time, I've had a situation where I've bought a round-trip refundable ticket, then needed to refund the return portion. When I call to request this, invariably I am told that I can't have the return segment refunded just because I didn't fly it, without the agent even looking to see if it's refundable fare. They must get this question so often from customers with discount tickets that they just answer it reflexively. When I ask them to look carefully at the fare, they always seem surprised.

This is the situation where I find 800-WE-CARE2 to be helpful. Most of the complains you see about that line here are people that for whatever reason want a rule waived for them (because they think it's unfair, because they think they have a special situation, etc), or want compensation where none is warranted or want an unreasonable amount.

In the very occasional situation where I run into a situation like yours, where an agent is clearly not implementing the rules properly, 800-WE-CARE2 gets the problem solved.

I think that's a valid comment. If you genuinely just forgot to cancel, that's one thing. But checking in and then no-showing does create a situation at the airport, especially for a first-class seat, where the gate agent has to process an upgrade at the very last minute. The courteous thing to do would be to let them know you're not flying.

It isn't "very last minute" to process. It happens at T-10 minutes, along with the other battlefield upgrades. I don't think it is really that big a deal for the GAs to process it.