By now you have discovered that, with some exceptional exceptions, the BA RTW boffins are not the sharpest pencils in the pack. In N. America use the AA RTW desk for all things that you can. That may not extend to complicated reissues, as I sadly discovered a couple of weeks ago, but luckily I knew what I was doing when I got into it with the BA people in the Toronto call centre.

'A' class availability can indeed be a problem on some flights - ORD/DFW-ANC for instance, or ORD/DFW-HNL. I thought I read somewhere on the AA board (?) that since RTWs and mileage/VIP upgrades both book into A inventory, that there was some pecking order that gave RTWs priority. I don't see how that could work - once you're confirmed into A on a mileage u/g it's yours. So a Y downgrade may occur if your flights are full up front. Fortunately, date/flight changes on xONExs are free. This is where knowing how to use various availability tools become important.