Refund refusal

I purchased a ticket but the time slot was incorrect after few minutes I realised that I bought a morning ticket instead of midday one. I requested a refund immediately on the 10th of December 2025 till today they are still processing my refund, even their customer service is not willing to help, they keep on changing their turn around time. They first said it's 7 to 15 days ,7 to 21 days, anything between 7 to 31 days. Since they are holding my money I feel I need it with 21 percent interest