I've been taking multiple trips on a good Choice Plus fare between XXX-XXX and gaming the Same Day Flight Change to add segments and miles.

Using EF, I've found E-bucket-available 4 segment routings (ea way) for as many as 11,000+ miles RT, on what would ordinarily be 2 segments (ea way) for only ~6,000.

Usually I've been able to request the exact flights and have the res agent just re-ticket me, but occasionally the agent has decided to call the rate desk -- at which point the process seems to stonewall: "your ticket isn't eligible," "we can re-ticket you for another $2,700," etc. etc. Rate/tariff tells the phone agent that what I'm requesting violates the ticket rules and can't be done -- but I have yet to be told why, or which exact "rule" is being violated.

Once referred to the rate desk, however, the caper is DEAD. The PNR gets annotated, and no one I might subsequently call or speak to at an AC is willing to act. That happened night before last, on my outbound, so I sucked it up and just flew on the original routing.

On my way home today, I tried the same thing again on my return. (I always book as two separate 1Ws.) EF showed last minute availability on a revised routing (+1 segment, +~1400 miles), and a friendly/willing agent put me into it with less than 30 mins to spare.

Shortly afterwards, my account got LOCKED. Now I'm 2/3 of the way home, and the specific Corp Security person handling my cycle can't be reached -- nor can anyone else tell me what's up. AAdvantage CS did say I had been sent an email about it, but that they had no access to the particulars, either. No email then, none since.

Interesting situation. It's not impinging on me directly right now: I expect I won't be denied boarding on my final flight of the day. But I'm apprehensive about the big picture here.

I've -- honestly! -- been doing only what I THOUGHT would be permitted under the free SDFC provision of these Choice Plus fares: i.e. finding an E available routing, within the 12-hour window, that wouldn't alter the origin and destination cities, nor add any stopovers, but would give me a few thousand extra miles each way.

I've got a feeling now, however, that I might be mistaken. This might work occasionally, but as a pattern... ???

Will keep y'all posted as things develop.