Turkish Airlines Didn't Refund for the Refundable Ticket

On 28.10.2022, I purchased a round-trip ticket with an additional fee for a refundable option, with reference number uanpjn. However, my return ticket was not changed by THY due to a strange reason, stating that 'the class of the ticket you want to change is no longer available,' as if it was my fault. Only approximately ₺6,000 was refunded to me. The reason I bought refundable tickets was to avoid such issues and to ensure a refund in the worst-case scenario. I expect a reputable company like THY to correct this mistake as soon as possible and reissue my rightful ticket. Due to the fluctuating exchange rates in Turkey, I am currently unable to secure a return ticket and urgently request that this grievance be resolved promptly.