Issue with Seat Selection on Turkish Airlines Flight

I purchased a two-person plane ticket and seat selection with THY, but when I tried to check in, I was assigned a different seat number than the one I had previously purchased. The seats that were supposed to be next to each other were given in separate locations. I contacted customer service multiple times, and each representative gave me different information. One said the seats were as I selected but couldn't be checked in, while another said I had only purchased one seat, not two. When I asked how it was possible that I received an email for two seats and provided a screenshot of the payment for two seats, they couldn't answer. This is not the first time I've encountered such unprofessionalism with THY regarding seat selection. Unfortunately, my flight will have already taken place by the time this is published, so I don't expect any resolution here. But be aware that buying a seat with THY means nothing; seats are assigned arbitrarily.