I Received Only Half of My Neck Pillow and Seatbelt Pad Order

Through Trendyol, I placed order number 10372862488 from the Sekutuning store, purchasing 4 neck pillows and 4 seatbelt pads for a total of ₺559.98. However, I only received 2 neck pillows and 2 seatbelt pads—essentially just 1 product set. The value of the missing items is ₺279.99. I have a video recording of the package being opened, clearly showing that the items were incomplete and the package was undamaged during shipping. After the order, I reported the issue by submitting a request to Trendyol, contacting Live Support four times, and messaging the seller directly. Despite all this, no progress has been made in over a week, and no solution has been offered regarding the refund for the missing items. I am requesting a refund for the undelivered products and, due to the prolonged lack of resolution, I now demand that my issue be addressed urgently.