Turkish Airlines Seat Selection and Service Quality Issue

Despite wanting to make a paid seat selection with THY, we encounter payment errors even though there are no issues with our bank cards. We spent an exaggerated 120 minutes trying to connect with a customer representative and barely managed to get through. They also couldn't process the payment. It is inexplicable why we face difficulties in seat selection with the same bank card and other cards that I had no trouble using to purchase my ticket. THY customer service used to be efficient, but in recent years both the staff and the online application and website have become very subpar. I created feedback but received no response. With only 19 hours left before my flight, I am very upset about the ordeal of trying to sit next to my mother, which has made me lose interest in going on vacation. I hope THY reviews this management style.