Turkish Airlines Ticket Issues for Ankara-London Flight

I purchased a Turkish Airlines ticket for the Ankara-London flight on 09.06.2024. When I bought the ticket on 25.03.2024, I was entitled to certain online services such as purchasing extra baggage online and online check-in. However, these rights were revoked by Turkish Airlines due to the flight being operated by A****, a J**. Despite contacting customer service three times and submitting two feedback forms, I only received meaningless and inadequate automated email responses. It's unbelievable that such an issue occurs in one of our country's prestigious institutions. It's not just about causing inconvenience to hundreds of people, but also failing to provide a solution despite extensive advertising is astonishing. I am sharing my complaint here because I want this issue to be known everywhere.