Crypto wallet and exchange Coinbase has admitted that some customers were erroneously overcharged for credit and debit purchases of crypto, and promises to reimburse all affected customers in full, the Coinbase blog reports Thursday, Feb. 15.

According to Coinbase, the problem was initiated when banks and card issuers changed the merchant category code (MCC) for crypto purchases earlier this month. This meant that crypto payments would now be processed as “cash advances,” meaning that banks and credit card issuers could begin charging customers “cash advance” fees for crypto purchases.

Coinbase wrote on their Reddit page at 6:00pm PST that the extra charges were a result of Visa reversing and recharging transactions due to the MCC code change. Their Reddit update adds that Coinbase is working with Visa and other major credit card network to create a new MCC for crypto purchases, and that they “hope that this will not have additional ‘cash advance’ fees” for customers.

Comments on Coinbase’s blog reflect the frustration of customers affected in a larger way when the multiple charges made to their Coinbase account led to overdrafts of their bank accounts. Medium user Sam Yoo writes,

“Are you going to refund the overdraft fees that were incurred from this fiasco?”

Reddit user Ipzi posted on Coinbase’s Reddit page that he was charged with 50 duplicate charges for a total of $67,000.

The Coinbase blog writes that any customers who purchased crypto on their exchange between Jan. 22 and Feb. 11 could have been affected. Any Coinbase customer that has been affected by extra charges is asked to report to Coinbase in order to help them track down what exactly occured.