I completely agree that justfly is a scam... they will mark lowest fare, but then extract the money from your pocket to make the tickets much more costlier than all other websites.
On top of that, their rude customer reps will torture you on phone with broken english.
I booked the tickets for my wife, who was traveling with an infant. justfly marked the lowest possible price, and their website didn't have any option to add infant with the passenger.
Airline told me that you need to call the travel agent (which was justfly) to add the infant. and when I called justfly back, they charged the enormous fee for adding the infant.

I was getting flight ticket with infant from different websites for $900, but justfly quoted $850 on their website.
There was no option to explicitly add infant on the justfly, but other competitors websites had it. May be, that is why competitor's websites were quoting higher price.
I booked through justfly (because it was quoting lowest price), and then spoke with the airline to add infant. Airline told me that i need to call justfly to add the infant, and price for adding infant should be between $80 to $100.
When i called justfly, their asked me for $200 extra for adding infant, and that bumped up the ticket cost to $1050. Almost, $150 more than the competitors, who were giving pricing with the infant.
Technically, just fly quoted lower price to win the purchase, without disclosing the price for infant (because there was no option to add the infant), and later on charged much higher price than competitors.
This is such a big scam.