Why does changing a oneworld classic reward booking with Qantas cost this much?

Has anyone had problems changing flights in a oneworld classic flight reward booking?
I have an 11 flight booking in economy class which cost me 140000 QFF points in Dec 2017. Now, I have enquired about possibly changing a couple of flights. Am am surprised that, in addition to additional taxes etc and the 8000 + 5000 points fees, Qantas seems to be asking me to pay 240000 points for the booking even though in my opinion the modified booking would still be fully complying with the rules for the 140000 points itinerary ie only one world airlines, under 35000 miles, only 5 stopovers, less than 15 connections, etc. Has anyone else had this experience and if so what did they do about it?

Hi ianj,

If you are absolutely certain you have remained within the guidelines for a RTW oneworld Qantas redemption, by all means escalate to a manager/supervisor. Otherwise, you can try hanging up and calling again. I noticed the wait time is much shorter at night and on weekends. Good luck.

Double check the guidelines listed here - PointHacks Qantas RTW guide

Thanks.  Fees for changing are: service 8000 pts and change 5000 pts.