Air Albania Changed My Flight Time Without Notice

I purchased round-trip tickets from Air Albania on June 15. The departure flight time was changed, and we were not informed in any way. We completed our check-in a day before, and it was confirmed. However, we missed our flight, and our fully paid vacation and events were ruined. Despite sending emails, we received no response. No refund has been issued. I want to file a complaint but don’t know how to proceed.