A one way new config XF popped up last minute for the return portion of a flight so I grabbed it. Seemed like a good deal. I still have my return S reservation on the same flight.

Should I do anything or call and try and cancel the S res or just ignore it?

Flight is Y5/C1 so not like its oversold. I know this is a slightly ticklish question as I've used round trips as one ways in the past.

The $500 copay + 20K for a C upgrade that wasn't going to happen didn't seem good.

It was an old C config 777 on the way out and I declined the upgrade for 3 seats in the back! So did a few other people I talked to, so C didn't go out full.

I guess I'm paying the LHR departure tax twice but don't expect much sympathy for that.