Overcharged taxes/fees after modifying booking?

[grey fantail]

Hi all,
I have a Qantas oneworld award booking that I have had to modify twice, paying additional taxes/fees each time.
However, on my latest ticket only the initial payment and the last payment are showing - the second payment I made when I first modified the booking is not there.
So I am wondering whether it is possible that the second payment was an error?
Using google flights to estimate the taxes/fees, I get c.$992 in total.
This isn't too far off the total of $1061.75 shown on my latest ticket.
But including the $260.05 that I paid when I first modified the booking would put the total well over what google flights suggests.
Is contacting Qantas to query whether the second payment I made is correct likely to be worthwhile?

 

[encryptededdy]

Can't you just put your full itinerary into the website and see what the taxes/fees are, and compare that to the total amount you paid?

 

[grey fantail]

The itinerary includes two stops that I can't put into the multi-city booking tool (Sao Paulo and Doha).
Plus some of the award flights I am using are booked out and no longer show up on the website at all.

 

[encryptededdy]

Ah, I see. I was going to suggest you could just check on different dates (since afaik the taxes & fees remain the same regardless of date)

 

[grey fantail]

Thanks for the suggestion encryptededdy.
I just found all the award flights by trying dates further in the future.
The total of taxes/fees comes to c.$1278 (depending on exchange rates).
Not too far off what I was charged in total.
So I probably wasn't overcharged after all.