Card provider Visa has dropped WaveCrest, a company that issued cryptocurrency-linked debit cards, from its network.

WaveCrest, which granted physical debit cards linked to cryptocurrency wallets to its users in Europe, violated Visa’s operating regulations, according to a statement the company gave to CNBC last week.

WaveCrest, said Visa on the matter, “was required to close its Visa card products, some of which were linked to cryptocurrency wallets.”

All of WaveCrest’s Visa-supported cards—which were also provided to other payment services across Europe, including TenX and Wirex—were “shut down in a second,” Dmitry Lazarichev, co-founder for Wirex, told CNBC, adding that WaveCrest had not responded to his requests for more information.

Since the cards were shut down, Lazarichev has received thousands of calls from “frantic customers” regarding their closure, he said. Wirex has issued approximately 500,000 crypto-enabled debit cards across the globe, according to Lazarichev.

Read more at CNBC and PYMNTs.

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