Turkish Airlines Refund Issue for My Ticket

I decided to use my right to a refund for a travel ticket I purchased for Malta due to a schedule change. However, during this process, Turkish Airlines requested the credit card used to purchase the tickets in bulk, even though it was their agency's card, not mine. They knew this card was never in my possession, yet they insisted on seeing it for the refund. This situation leaves us, the customers, at a disadvantage. Large organizations with big budgets are happy with the ₺5000-₺7000 they withhold from us. I wanted to address this issue under Turkish Airlines, but it seems they are not responsive. I believe this issue also concerns Turkish Holidays, as it happened during my travel plans. I will try to report this complaint wherever I can. All I want is to get my ₺7000 back, the cost of my tickets. Despite not having the agency's card, they continue to insist on it. I want someone to explain why they are asking for the agency's card and find a way to return my money.