Commission-free swaps seem attractive at first but using a service like Changelly to do it through doesn't. Like ChangeNOW, those are selective scammers. They are legit enough to not be called complete scammers but love to hustle their users every now and then and when the spoils are worth the negative press. I would be very careful with them, and use them with small amounts only and as a last resort if there was no better service around for the same swap I needed to do.