When tech executive Sean Everett had his Coinbase account drained in a hack last month, the pain of the financial loss was aggravated by Coinbase’s slow response. After an initial message that day to get more details about the hack, it took Coinbase two weeks to answer his request for a refund, which was denied because the breach originated through his cellphone account.

Coinbase's slow response wasn’t unusual for cryptocurrency startups. The sudden rise in popularity of digital currencies in recent months has caught online exchanges and currency storage companies off guard, leaving them racing to process an overwhelming number of customer support requests.