The following is a joint statement from Visa and Worldpay:
Over the last two days, some customers who used a credit or debit card at Coinbase may have seen duplicate transactions posted to their cardholder accounts.
This issue was not caused by Coinbase.
Worldpay and Coinbase have been working with Visa and Visa issuing banks to ensure that the duplicate transactions have been reversed and appropriate credits have been posted to cardholder accounts. All reversal transactions have now been issued, and should appear on customers’ credit card and debit card accounts within the next few days. We believe the majority of these reversals have already posted to accounts. If you continue to have problems with your credit or debit card account after this reversal period, including issues relating to card fees or charges, we encourage you to contact your card issuing bank.
We deeply regret any inconvenience this may have caused customers.