My Mytrip Flight Cancellation Problem

When I tried to cancel the flight I purchased, not only did they refuse to refund my money, but they're also demanding a service fee. How can such a ridiculous policy exist? They won't even allow me to cancel through their system. I bought a ticket from Romania to Antalya. But since my plans changed, I'm trying to cancel my ticket a week in advance. The Mytrip customer representative says this isn't possible. Not only am I not getting a refund, but they're asking for additional money. They've turned this into a highway robbery situation.