Turkish Airlines Price Difference Issue with Anadolu Jet Ticket

I purchased round-trip flight tickets from Anadolu Jet for the dates July 26 - July 30, 2023, and had them open-ended before the travel date. Today, when I called to use my open-ended tickets, Anadolu Jet representatives informed me that I could use my tickets with Turkish Airlines. I don't understand why I have to pay more to use my tickets with Turkish Airlines when Anadolu Jet has become AJet. I believe customers should not be held responsible for the change in the airline. I am experiencing a price difference issue. I have to pay an additional ₺600-₺700 for tickets I would buy on the same day. Moreover, while cheaper prices can be found on intermediary flight ticket websites, an additional ₺120 fee is required because the open-ended ticket must be purchased through the call center. It is not allowed to purchase the open-ended ticket from a different source. This situation constitutes a violation of consumer rights. I expected my ticket, which I bought from Anadolu Jet and later turned into AJet, to be transferred accordingly. I have already paid an additional ₺600 to make it open-ended. I request a full refund of the amount I paid or a new ticket from AJet.