I have a ticketed ex-Japan DONE3 (issued by CX 18 July) which I need to change.
It currently routes HND-xHKG-JFK-SFO-xORD-ATL-ORD-xMIA-BCN-HEL-xLHR-xDXB-xLHR-PVG-KUL-xSIN-HND departing mid Oct.

I need to change the ATL stop to RDU. I'm trying to get a reprice in the online tool with the change to check for any tax changes in addition to the 125USD change fee, however the tool is popping out errors when I try to check.

Is there any other way to get an actuate costing of the revised routing?

Codes used:
CX HND-HKG
AA HKG-BCN
IB BCN-HEL, LHR-DXB
QF DXB-LHR
MH HEL-LHR, PVG-SIN
JL SIN-HND
BA LHR-PVG