I’m trying to book my parents in PE and upgrade to Club GVA-LHR-JFK-LHR-GVA. Doing just the cash part of the booking online, I of course get Swiss POS, but I’d rather not pay in CHF as I lose on the FX fee and don’t get the triple avios. But on the phone via GGL line I get the UK POS and it’s like £600 more expensive.

Is there any way to have my gâteau and eat it too and have the GGL agent book using the Swiss POS?