Does not deliver and then won't refund

I placed an order on 15 May 2022. The promised time for delivery was 10 days. However, by August, it had still not arrived and after complaining, they cancelled the order on 8 August and told me that I would be refunded, but that it may take some time because there is a refund queue. A month has passed and they have still not refunded the money. I have now decided to institute legal proceedings to recover my credit balance, as it seems to me to be the only way to get a refund.