Cyufjy

I bought a ticket to fly with LATAM tomorrow on Tripsta. A few minutes ago, when checking in, I discovered my flight was rebooked for the next day, and it was changed to fly through different cities.

I haven't received any information about this. If I hadn't checked on the website, I would have discovered at the airport tomorrow that my flight actually leaved 15 hours later.

In my case the new flight is actually better (it's much shorter) so I'm happy with the change, but if I wanted to complain to someone about lack of communication, is it the airline or the website where I bought the ticket?

Interesting question. I think the airline doesn't necessarily have your contact information (depending on how you booked), so the website (company) you booked through should be responsible to inform you: I recently got flights booked through an agency, and exactly the same happened. I also logged in to the airline with the booking code to pick a seat, and found the changed flights. The contact email in there was another agency's email somewhere in South America, and they probably ignored the change email if they ever got it. I changed the email online to mine, and got further change notices that way.

kayak.com et al probably get a gazillion flight change emails every day from all the flights they sold, so they potentially just ignore them - what a nightmare to match them all to the right bookings and forward them. I don't know if you can ding them for it - probably the fine print says it's your responsibility to 'contact the airline a week before the flight and verify it'.