When did you request the TK mileage credit from MileagePlus? You have six months to request. If your request for missing mileage was put in after 8/16-8/19, it will be denied because you waited too long.
And are you sure you booked into Y? Full fare economy on that route is about 2000 TRY. Is that about what you paid for your ticket?
And were your flights operated by Turkish Airlines or by EgyptAir? Turkish Airlines and EgyptAir codeshare on that route, and even tough your ticket may say TK it may have been operated by EgyptAir. What was?