Unable to Cancel Fly One Flight Despite Requesting Early

I booked a round-trip flight with Fly One for my outbound and THY for my return through Enuygun.com. Unfortunately, I made a mistake with the dates and selected the wrong month. When I realized this, I immediately contacted Enuygun.com for a date change. They told me it would be more expensive to change the date than canceling the ticket, so I canceled my THY ticket. However, Fly One refused to cancel my tickets, despite Enuygun.com directing me to contact them. Even after contacting Fly One by email and accepting the cancellation fee, they still said they couldn’t cancel the tickets. How can two tickets be non-cancellable with days left before the flight? Enuygun.com has been unresponsive and disappeared, leaving me stranded with unresolved issues.