SunExpress Airlines' Unfair Charges for Antalya-Van Trip

I booked a round-trip flight from Antalya to Van and Van to Antalya (V2K) on August 24, 2023, at 16:06, for 3,999.96 TL. To my shock, less than 24 hours later, on August 25, I discovered that the exact same flight was being sold in the same direction, under the same conditions, for less than a third of the price (from 999.99 TL to 329.99 TL). As a Sunexpress member, I hadn't received any notification about this drastic price drop, despite having clear consent for notifications. I called customer service and was told that no changes could be made. They advised me to return my tickets and repurchase them at the new lower price. However, they only offered a refund of 2059 TL with a deduction of 1940 TL. This calculation doesn't add up, as the total deductions should be 307.44 TL. I urgently request a fair resolution, a refund of the excess charges, and the option to repurchase the ticket at the discounted rate.