watch nowAfter two decades going to Starbucks every day at 4:30 a.m., longtime customer Tony Dennis abandoned the company last year."I was frustrated," he told CNBC.The customer experience he used to love had disappeared. Baristas didn't engage with him, despite his daily visits. At the same time, the cost of his double-shot tall nonfat lattes and double-shot tall nonfat cappuccinos kept climbing.The 65-year-old Las Vegas real estate developer wasn't the only Starbucks customer who no longer felt the same l ...