For an upgrade on the solely JFK-LHR sector from WTP- CW I'm getting;
Security Service Fee - USA$5.60
International Transportation Tax - USA$19.70
Passenger Facility Charge -$4.50
Carrier imposed charge$275.00
Security Service Fee - USA
$5.60
International Transportation Tax - USA
$19.70
Passenger Facility Charge -
$4.50
Carrier imposed charge
$700.00
Thus a difference of 25000 Avios and $425. I'm hoping I've made a mistake