Unable to Check-in for Sunexpress Flight Booked via Trip.com

I purchased a Sunexpress flight ticket from Izmir to Birmingham through Trip.com, but as my departure date arrived, I still couldn’t complete my check-in or access my ticket invoice. Trip.com’s customer support has been entirely unhelpful; every response from their assistant is automated, and despite repeatedly reaching out, I receive no real assistance. This is highly frustrating, especially with my flight approaching, and I urgently need help resolving this issue. I expect Trip.com to address this promptly and ensure I can check in without further delay.