After allegedly draining bank accounts, Coinbase promises refunds (update)

Nobody likes being charged twice for the same transaction. It's a hassle, particularly if your bank account is nearly empty and you get hit with an overdraft charge, too.

Coinbase, a popular way to buy, sell, and store digital currency including Bitcoin and Etherium, is now being accused of charging some of its customers five, 17, or even 50 times for the same purchase to the point those customers went broke -- and it's not yet clear what's going on.

The good news: Coinbase has now admitted to a duplicate transaction issue, and promised full refunds for any and all affected customers.

Here's the full statement we received Wednesday afternoon:

We're currently investigating an issue where some customers were charged incorrectly for purchases of digital currency with credit and debit cards. This is related to the recent MCC code change by the card networks and card issuers charging additional fees. We have identified a solution and future purchases will not be affected. We will ensure any customer affected by this issue is fully refunded. We expect these refunds to happen for customers automatically through their bank. If you believe you were affected by this issue, please contact support@coinbase.com. We will be reviewing all card transactions from the last few weeks to ensure all affected customer are notified. We will post on Twitter and our blog with further updates. 

Watch this: Coinbase charged customers multiple times for purchases

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The company's also promising a full blog post within the next 24 hours to explain what happened, and is keeping the Reddit community up to date in a post right here.

Update, 6:11p.m. PT: Coinbase has just blamed Visa for the duplicate transactions, in a series of tweets. Visa didn't immediately respond to a request for comment. 

Update, 7:17p.m. PT: Coinbase VP and GM Dan Romero tells CNET the company is still investigating exactly what happened, but says that Visa "retroactively reclassified" a number of transactions in a way that should have involved reversing a transaction, then charging a second time, but that the reversal step failed. "It clearly didn't work for a large number of customers," said Romero.

"We're in communication with Visa to make sure all affected customers are reimbursed," said Romero. "We're going to do our best to do this as quickly as possible, because ultimately customers are going to hold us responsible."

Update, 9:55 p.m. PT: Visa's statement on the matter: "Visa has not made any systems changes that would result in the duplicate transactions that are being reported. We are also not aware of any other merchants who are experiencing this issue. We are reaching out to this merchant's acquiring financial institution to offer assistance and to ensure cardholders are protected from unauthorized transactions."

Update, Feb. 20 at 4:08 p.m. PT: Visa has agreed that Coinbase was not at fault for the duplicate transactions, and issued a joint statement with payment partner Worldpay (who, we understand, facilitated Visa transactions for Coinbase) to that effect. You can read it here:

The Verge interviewed a number of affected customers, and you can read their stories here.