The case of overbilling: Coinbase accuses, Visa denies :

Although, Coinbase has had its fair share of technical problems in recent months, it seems that the last one may not be his fault. The Coinbase exchange accused Visa of making unauthorized cash withdrawals from the accounts of some users who purchased cryptocurrencies, but Visa denied.

A Coinbase bug ...
Since 2017, users of Coinbase can link a credit or debit card to their account and buy cryptocurrency immediately. Some users, however, have observed a duplication of transaction fees. In some cases, their bank account was emptied and overdraft fees were even billed.

This situation was publicized after users of Coinbase rushed to Reddit. It is on this platform that they came to complain that the exchange has invoiced them several times the same transaction. Some buyers claim that they have been charged up to 17 times the expected purchase price.

Coinbase has since assured users that accidental charges will be reimbursed. Unfortunately, the company was not able to provide a precise schedule for repayments. But the exchange said it worked with banks to guarantee repayments.

... or a Visa maneuver?
On Thursday, Coinbase released a statement in a series of tweets in which she said that Visa was to blame for the problem.

In addition, Coinbase Vice President Dan Romero explained that the big banks and card issuers had asked the card networks to change the code of the merchant category for the purchase of digital currency.

This code change would allow banks and card issuers to charge additional fees on digital currency purchase transactions. Therefore, Coinbase's services are now categorized in the Merchant Category Code as cash advances. The exchange said it is working with major card issuers to fix the problem.

Conversely, Visa indicated that it had made no changes that would have doubled the price of transactions. The company said in a statement sent to CNBC:

"Visa made no changes that would have duplicated cardholder transactions. We are also unaware of the existence of other traders having a similar problem "VISA Public Relations

As Visa and Coinbase argue over who should take responsibility for this huge blunder. Investors affected by the mistake claimed that the accidental multiple charges had almost emptied their bank accounts. Others said they were thinking of closing their Coinbase account.