Same thing happened here
I bought three AF award tickets EWR-CDG using AF, DL, and NW miles. [Will hereafter be consolidating in NW for each member.] The costs for each were
NW $76.95 [booked online, $76 taxes]
DL $96.95 [Had to book via agent = $20]
AF $316.75 [booked online, $210 + $107 taxes]
It's frustrating to pay $210 for a fuel surcharge!