Viagogo Sold Tickets for Canceled Event, No Refund

I purchased 2 tickets for the Özcan Deniz event to be held on 17 June at Ankara Altındağ Cermoderm via Viagogo, for a total of approximately ₺18,000. I trusted the site and completed my purchase, but I later found out that the event had actually been cancelled long before that date. One day before the event, I called Cermoderm to confirm, and they told me that the event had been cancelled months ago. In other words, Viagogo continued to sell tickets for an event that had already been cancelled. After learning this, I contacted Viagogo customer service and requested a refund, but they simply replied that they could not do it and refused to refund my money. I find it unacceptable that tickets for a cancelled event are still sold and that, even after the cancellation is confirmed, my refund request is rejected. I request that the full amount of approximately ₺18,000 I paid for the two tickets be refunded to me as soon as possible and that this grievance be resolved.