SunExpress Online Check-In Not Working Despite Seat Purchase

I am very frustrated with SunExpress due to the ongoing issues with online check-in. When attempting to check in online, I receive an error saying "passenger not found." Calling customer service hasn’t helped either; they simply say the system isn’t working. Yet, when I try to purchase a seat, assistance is provided instantly, and the transaction goes through without a hitch. Even after purchasing a seat, I’m still told I must complete check-in at the airport. SunExpress needs to address these system errors and ensure that online check-in is available, especially after customers have paid extra for seat selection. This problem is inconvenient and time-consuming and needs immediate resolution.