All refunds are issued via the same payment method that they were placed. Once you have contacted customer service and it's been confirmed that the refund has been issued, please allow some time for the funds to reach your account.
For card payments, depending on the bank that you use, refunds can take 5-10 days to appear. If the refund was issued very shortly after the payment was initially made, the card issuer may have simply cancelled the payment. if you haven't received a refund, please also check that the original payment is still shown on your account and it has not been cancelled. If the payment has not been cancelled, and after 10 days you have still not received a refund, please contact customer support.