Turkish Airlines, Anadolu Jet, and Ajet Seat Selection Issue

Turkish Airlines, Anadolu Jet, and Ajet Seat Selection Issue
I have chosen Turkish Airlines for at least 100 international trips and whenever possible for my flights. After Turkish Airlines canceled their SAW flights in recent years, I was forced to choose Anadolu Jet for my SAW flights. Since my home is 15 minutes away from Sabiha Gokcen Airport, I bought an Anadolu Jet ticket for the SAW-AMS flight on April 7, and a THY return ticket for the AMS-IST flight on April 14.
Following the separation of THY and Anadolu Jet operations, my existing Anadolu Jet ticket with an Extrajet package (free seat selection option and baggage allowance) was transferred to Ajet.
Weeks of Seat Selection Issues!
Since this transfer, I have been unable to select a seat through the THY system (mobile app and website), the Anadolu Jet-Ajet system (mobile app and website), or by contacting THY customer service despite calling multiple times and submitting complaints (##TK-10601035##). I have received no support, information, or response.
I want to do online check-in for my flight tomorrow morning, and the system still gives an error!
When I called the THY call center again, they told me to call the Ajet call center.
Additionally, I have been waiting for 50 minutes to connect to an Ajet customer representative and still waiting. For the last 30 minutes, the estimated wait time has been 2 minutes, and I am writing this complaint during this time! I will probably not wait any longer!
Unfortunately, this is the worst service quality I have ever experienced!
I regret to state that no one has the right to bring such a prestigious institution and its services, which are the pride of the Republic of Turkey, to this situation.

