I've heard that it might be illegal for a reseller like lastminute.com or tui.com to sell a ticket at a lower price than the one offered by the airline itself and that the company, if it finds out, can cancel the ticket and offer a refund.
Example: suppose there's a ticket with Alitalia from Rome to Tokyo at 600 Euros. Can a reseller apply an "online discount option" and sell it for 570 Euros (no matter how much the reseller spent to buy the tickets). I was told that they can't by a tour operator and I'm very skeptical about it.
Fact or Fiction?
[There may be different reasons of why a reseller wants or can sell a ticket at a lower price, but this is out of scope of this question]
[I'm also not talking about full packages that may include hotel etc. Just plane tickets]