Difficulty Contacting Turkish Airlines Customer Service and Ticket Issue

THY customer representatives don't seem to know what they're talking about. I've called 10 times, but they still haven't resolved my problem. Every day, I'm put on hold and asked to open a new feedback. I want to send my sister as a companion for our disabled passenger, but I'm told to upload all the documents. They say they will add them, and then I receive an email saying I need to complete the process at a THY branch. It seems they don't understand Turkish, German, or English. Now, because we were not informed that the companion and disabled tickets must be purchased together, we have to buy a ticket that is €60 more expensive. They are still sending emails saying, 'Please purchase your companion ticket from any THY seller.' While billions are spent on the Champions League, no discounts or promotions are offered to their own citizens. It's a shame.