I flew to ORD-JNB (through FRA) on LH and SA in C-class, and the flight and seat were amazing. I'm in JNB for three months for work, and I get a one week fly-back to the US. Unfortunately, my firm will only pay for Y-class for the fly-back. What are my options to upgrade (if any)? UA's SWUs are only confirmed on UA and on good for stand by on LH. Is there any way to upgrade on SAA or do I have to sit in Y?

My firm offered BA's World Traveller Plus (Premium Economy), but I don't can't give up all those UA miles. Any advice? Please...

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