Apple is not a bank. It does not and cannot handle funds.
When you initiated a refund request, the merchant’s instructs his bank to send funds back through his credit card processor and then through the Payment Network Processor (Mastercard or Visa or American Express etc.) and then to your bank Legally the merchant can take up to 30 days to complete the refund process.
Apple played no part in the processing of your refund. Please contact the merchant and request the ARN, Acquirer Reference Number, which is how refunds are tracked.
If the merchant can’t provide the number, they are scamming you. If you receive the ARN, contact the bank that issued the credit card you used and provide the ARN so they can track your refund.
If the merchant can’t or won’t provide the ARN, dispute the with the issuing bank.
Im sorry this has happened, especially at the holiday season. But, this isn’t an Apple issue. If I can assist in any way moving forward, please don’t hesitate to respond.