Turkish Airlines Canceled My Return Ticket Without Notice

I had a problem with my flight tickets (PNR: VJPA7T) for the Istanbul-Amsterdam flight on 22.06.23 at 19:20 and the return flight from Amsterdam to SAW on 27.06.23 at 16:20. On June 22nd, when I realized I missed my flight, I contacted customer service to inquire about the possibility of catching the flight or any delays. I was informed that it was not possible and asked about a refund or change options, but since there were less than 2 hours left, I understood that it was not an option and accepted that I missed the flight. Unfortunately, I was not informed that my return flight would also be canceled along with this flight! The next day, I flew to Amsterdam with another airline along with my family (my spouse, 2 children, and myself - 4 people). During my 5-day trip, I did not receive any reminder or warning message from Turkish Airlines stating that my return flight was invalid. (I believe this should have definitely been done). As someone who missed a flight for the first time in my life, I was unaware of such a rule. If I had received such a warning, I would have taken precautions and planned accordingly. Remember, I believed my return flight was still valid! On the morning of June 27th, at 07:00, I checked in for my return flight using the Turkish Airlines mobile app because this flight was still active among my flights on the app. I even paid for seat selection with my miles points for this flight, which you had already canceled. Thinking everything was normal, I went to the airport with my family on time. At the counter, the staff informed me that I could not board the flight. When I showed my check-in, I was told the sentence that should have been mentioned, reminded, or warned 5 days ago: 'Since you missed your outbound flight, your return flight has also been canceled.' Now, please empathize and put yourself in my shoes. I have been a systems engineer for 25 years, and I believe this is a clear bug. I had two discussions regarding this issue, and my expectation was to rectify this mistake by accommodating my family and me on one of the two return flights on the same day to resolve my grievance. Unfortunately, I received negative responses to both requests and for some reason, my missing the first flight was questioned in an unfortunately very unlucky manner. Dear official, I was not informed about the cancellations, allowed to check-in, and charged for the seat! I kindly request your assistance in resolving my grievance.