I Missed Turkish Airlines Flight Due to Lack of Announcement

On December 14th, we had a flight from Istanbul Airport to Cologne at 08:35 AM. Due to seat availability, we sat at gate C4 instead of C3. While waiting for the gate to open, we expected to hear an announcement, but unfortunately, since it was a silent airport, we missed the flight. I then had to go to Sabiha Gokcen Airport on my own and buy a ticket for the 13:25 flight. However, since my return ticket was automatically canceled due to the cancellation of the outbound ticket, I found out at the airport that my return ticket was also canceled. The night before, while checking in with your call center, I purchased extra baggage with miles; no one informed me about the cancellation, and I learned about it at the airport. As if that wasn't enough, I had to pay an extra 600₺ for a new ticket. Words are not enough to describe my frustration. Should I be upset about the unnecessary ticket I bought because the call center didn't inform me, or the fact that if I had been informed, I would have bought the outbound ticket at a discount in the first place? It's like a joke; we bought baggage rights for a non-existent ticket. This is not a corporate approach. Please review the camera recordings at the waiting area and the call center recordings to resolve my grievance.