Disappointing and Surprising Rules of Turkish Airlines

As a passenger, the experience I had with THY services left me extremely disappointed and I feel compelled to share my dissatisfaction. Initially, I purchased a ticket from Istanbul to Riyadh for 13,000 ₺. Due to personal circumstances, I changed the ticket status to an "Open Ticket" and when I attempted to reactivate it later, I contacted THY. I wanted to change my arrival airport from IST to SAW and from Riyadh to Medina. However, THY informed me that they couldn't make changes to SAW airport, only Ajet could. Yet, when I contacted Ajet, they stated they couldn't see tickets starting with the number 235 and advised me to contact THY again. After a lengthy and exhausting back-and-forth communication between the two companies, THY eventually accepted my request after initially rejecting it. The last agent I spoke with on the phone seemed surprised that they had initially refused to activate and change my ticket. Therefore, my first complaint is why THY employees refused to provide assistance until I resorted to raising my voice on the phone. The biggest issue is as follows: I originally purchased the ticket for 13,000 ₺, and the price for the ticket I chose to change to was approximately 6,000 ₺ in the THY system. Yet, they demanded about 8,000 ₺ over the phone! When I asked for the reason, they claimed it was because I didn't show up for the first flight. However, this doesn't apply to my situation because I had turned my ticket into an "Open Ticket." Therefore, I shouldn't have to pay a no-show fee. But they simply said, "This is the system, there's nothing I can do." Do you think I'm foolish enough to pay an additional 8,000 ₺ on top of the 13,000 ₺ I already paid for a 6,000 ₺ ticket? Following this experience, I request that you take the necessary steps to rectify the injustice and dissatisfaction I have encountered. Either a full refund or a complimentary activation for a new ticket is warranted.