Snatcher has snatched my money

After many years of good service, what a disappointment 2023 has been. In July I placed a big order and one small item was not included. After struggling for a bit, I finally got a credit voucher and used it the next time I ordered in August. I included the item again, and it was not in the box again. While fighting for that credit, I placed another order. On 19 September (4 weeks later) I checked and the order had still not been packed. As I was going to email them, I decided to check on the 21st of September, and the order was cancelled. After many emails, I finally got a phone call on 3rd October to say I must send my banking details and they will refund me. I sent the email off with my banking details. It is now December and I have sent quite a few emails - to no avail.