Mytrip Charged Me More to Change My Flex Ticket Than Buying a New One

I bought a flexible ticket through Mytrip and needed to change the date five days before my flight. During my call with their representatives, they asked me to pay an additional fee—₺3980—for them to update my flight to the new date. However, at that exact moment, I could purchase a new ticket for ₺3493 on the Mytrip website, and even the new Flex ticket was only ₺4052. They claimed the high change fee was because they had to rebook it under the same package. If you offer no real flexibility or advantage, why do you charge extra and market these as Flex tickets? I will also file a complaint with the Consumer Arbitration Board.