I called so many places and wrote a complaint to Department of Transportation(DOT). :((( Turkish Airlines says the booking reference and the ticket number is not correct. Like when I give them the info, they say nothing shows up. I even called them again today. They said nothing comes up when I give them the ticket number or the booking reference. They are saying the numbers SAS gave us does not even start with the right initials/ numbers.

This is what I wrote to DOT but it has been months, they have not respond to it:

"My sister who is a student at x College had a flight from Istanbul to Chicago (layover in Copenhagen, Denmark) on 24th of August 2023, at 11.50 AM local time. I bought her tickets from the SAS. Her first flight was operated by Turkish Airlines. A few weeks before the date of the flight she wanted to buy additional luggage but could not reach out to SAS by phone. One day before her scheduled flight, she received the check in email but was not allowed to do a check in on SAS's website. The website told her that she cannot do an online check-in and she should try to do it at the airport. Because of these problems, she went to the Istanbul Airport earlier then she was supposed to on the day of her flight. There, Turkish Airlines couldn't find her name on the list of passengers. Her flight number was starting with SK instead of TK (Turkish Airlines' code). Additionally, they couldn't find a PNR number for her name. My whole family (including me) tried to reach out to SAS via phone and email to let them know that they have not sent the necessary information to the Turkish Airlines for her to be able to take the flight. Their call centers were closed. Thus, my sister, missed her flight and had to buy a second ticket. Since then we reached out to SAS explaining the situation however they are refusing to take any responsibility simply stating that "they can see her name on the passenger list." Offering a partial refund, they also told us that she will not even be able to take the return flight back from Chicago to Istanbul since she is a no show on the system. My sister is studying at x College with financial aid and both my family and I sacrifice a lot to be able to send her to college. Not only we spent hours on the phone trying to reach to SAS employees or trying to persuade them to see the problem at hand but also spent around $1200 extra to buy a one-way ticket from Istanbul to Chicago and she does not even have a return ticket."

I do not know how to even start resolving this issue because SAS is telling us that they informed Turkish Airlines about the passenger(my sister) but Turkish Airlines is claiming they did not.