Turkish Airlines Bursa-Erzurum Flight Boarding Issue

I purchased an economy ticket for the Bursa-Erzurum route. I arrived at 17:05 for my flight that was scheduled to depart at 17:40. However, even those who arrived before 17:05 faced the same issue; we were not allowed to board the plane. The plane departed half-empty because we didn't arrive 45 minutes earlier. Many people, including myself, were affected, and we were told that ticket refunds are not possible. Not only did we travel all the way for nothing, but we were also informed that the ticket cost would not be refunded. The staff there mocked us by saying, 'This time the plane will go half-empty, what can we do?' I want my issue to be resolved and my ticket cost to be refunded. We even suggested, 'Let our baggage stay, at least let the passengers go,' but they didn't accept that either. These actions are not befitting of THY; people don't earn their ticket money easily. Please resolve our issue.