I have booked the following trip:

SGF-DFW-LHR-NCE outbound
FCO-LHR-DFW-SGF inbound

(SGF is Springfield, Missouri, FYI)

I booked this itinerary on BA.com, cash, no miles. The SGF-DFW and DFW-SGF segments are BA code shares on AA (Eagle) metal. The other segments are BA flights on BA metal. My booking class for the BA codeshares on AA are Y since these are single cabin RJs. The other flights are in I Club World and J Club Europe.

I had planned to do an upgrade to F for the DFW-LHR and LHR-DFW portions. However, BA.com under MMB had the upgrade option grayed out. So I called BAEC in the US. After speaking with the agent, who then spoke to her supervisor, I was told that I could NOT upgrade for the following reasons:

1. With a BA codeshare on non-BA metal, there is no ability to upgrade. The codeshare eliminates that possibility for the ENTIRE booking, even though there is no first class to which to upgrade on these RJ's.

2. As if that were not enough, my open jaw creates a problem since FCO and NCE are in two different zones. That makes it impossible to do an upgrade. Had they been in the same zone, no problem.

Okay, rules are rules, but these are ridiculous IMO. I have to admit, all my upgrade experience is on AA, and I am new to BAEC, so I have no experience with BA's particular quirks. However, I did my research (I thought), but I can't find these "rules" anywhere, not on BA.com or FT, so I had no idea that I should even be careful.

What makes no sense is that only one part of this booking could be upgrades to F, the DFW-LHR-DFW portion. I would think that the miles would be usable just on this portion as they is the only ones that can upgrade to F, are BA flights on BA metal, and thus don't violate any rules.

My question: I called the BAEC number for the US, so I assume the agent is in the US and thus so is her US supervisor. Any chance that a different agent, possibly one in the UK, would do this differently? Or is this a fairly consistent BA rule on using MFU? If so, I'll always be buying my SGF-DFW or SGF-ORD segments separately from the rest. And I shall get to experience Club World (I've done First, and it was quite nice, and I was looking forward to doing it again).

Thanks for the help!