Turkish Airlines XL Seat Booking Issue During Medical Emergency

My husband had a serious motorcycle accident on the second day of our holiday in Thailand, resulting in fractures in his leg and ribs. He was hospitalized for eight days. When we wanted to return to Turkey, the doctor stated that he could only travel with his leg extended. Based on this, I started looking for business class tickets. Thai Airways had a reasonably priced flight, but we wanted to return as soon as possible and thought we could have a more comfortable flight with Turkish Airlines. We saw that business class seats were full on the upcoming flights. Ms. E** from the Turkish Airlines call center suggested XL seats, stating they were available and that my husband could travel comfortably. The most important thing for us was that he could extend his leg, so we happily purchased the tickets. I specifically confirmed multiple times that he could extend his leg because, in addition to the fracture, there was severe swelling in his leg. Ms. E** noted this in our ticket and mentioned that XL seats were only available for purchase over the phone. The next day, when we went to the flight, we learned that our ticket did not include the XL seat and that those seats were full. I should also mention that we paid an extra fee for the XL seats. I called the call center multiple times; however, I either couldn't reach anyone or the people I reached said my husband couldn't sit there. They told us that if we canceled the ticket, we would lose 80% of the fare, and if we changed it, we would have to pay a penalty. We suffered without any fault of our own. I remember crying helplessly at the airport. We had to board the plane, and my husband couldn't find a place to extend his leg. He had to keep his leg down for eleven hours. I won't even mention the wheelchair issue at Istanbul Airport. My husband initially didn't want to buy a ticket from Turkish Airlines, but I convinced him. I realized how wrong our decision was. We paid a high price and were left in a difficult situation. Now, my husband is at risk of compartment syndrome, and his recovery process has been delayed by a few weeks. It has been six days since we filed our complaint on feedback sites, and we still haven't received a response. I will use all my legal rights to hold Turkish Airlines accountable for this negative experience my husband went through.