Coinbase has a problem. As interest in Bitcoin has soared along with its price, the popular cryptocurrency exchange has found itself the target of a growing spate of angry customers who haven’t been able to access customer service. A quick look at Twitter tells the story. As one upset user of the service ranted earlier today: “Multiple issues over the last month which cost me $$$ several open cases and 0% response?? When are you going to help me or is it easier to just forget. This wont be so…