(see update at the end.

(see update at the end.
TL;DR - DO NOT EVER ATTEMPT TO CLICK ON THE SEAT MAP, JUST DON'T TOUCH IT)

BE VERY CAREFUL BOOKING ON THEIR WEBSITE!
There are many hidden charges you have to manually opt out. BUT the worst is seat selection, it offer you a seat map and most people will automatically click on the seat. Then the section is collapsed and covered up, only showing a message "Thank you. Your seats have been selected.". However there is an ADDED "SEAT SELECTION FEE" being added and it is NOT SHOWING under "Support Package" but a very fine print and you have to OPEN UP under the Passenger section then the THIRD down arrow (after taxes and fee) to see.

The website is also design after you have entered the credit card information and a big "COMPLETE YOUR BOOKING" at the very bottom but NOT SHOWING THE AMOUNT being charge unless you scroll ALL THE WAY TO THE TOP again. (Even with that, those additional fee, like seat selection, are still hidden from view)

There is NO FINAL CONFIRMATION page like other website let you review everything you selected, once you click the big green button, that's it.

AGAIN, BE VERY CAREFUL TRIPLE CHECK EVERY SINGLE EXPENDABLE BUTTON ON THE SCREEN. SOME FEES ARE BEING ADDED AND HIDDEN.

I think the website is by design to hide the extra fee to make an extra buck, which I think it is kind of dishonest.

Oh, BTW the selection fee has a VERY fine print saying "We will share your seating requests with the airlines but cannot guarantee your request will be honored." Which may also explain why after you pay them the fee, you still CANNOT SELECT A SEAT on Air Canada website for example. IT IS A SCAM! So basically they are charging you EXTRA FOR NOTHING. No added value at all.
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UPDATE:
Called Flight Network, jumped through a few hoops (seriously). Long story short, the second agent I spoken to removed the seat selection fee at the end but not without some resistance and tactics.*

As soon as I explain how their website is covering the charges as soon as one clicked on the seat map, she seems to know about it.

To be fair, remember, you are dealing with the COMPANY and not individual agents. Since I get my desired outcome, I raised back to 2-stars. (or should I?)

Or maybe I was just lucky, I have read other posting online, some were unable to get their money back. Perhaps the expectation was set before the call and turns out it is better.

*the tactics?
"She claim she was able to assign seat on Air Canada flight, so she can only refund me the different."
1. She never mention there was a charge from AC for reserving seats (on top of the seat select fee) before making the selection for me
2. Then she claims AC already charged $20 per seat and cannot back out. But I quickly point out that's a lie, because on that flight preferred seat was $20, but the seat she assigned was NOT preferred seat.

Once I pointed out AC only charge $20 for preferred seat and the one she assigned wasn't. Her tone changed... so figure.