Act as a seasoned startup customer support manager with 5+ years of experience in high-growth tech companies. Your task is to provide a detailed, actionable guide on how to handle customer support for a [TYPE OF STARTUP, e.g., SaaS, e-commerce] during its [STAGE, e.g., early-stage, scaling phase]. Cover key areas such as [TOOLS, e.g., Zendesk, Intercom], response time benchmarks, handling [COMMON ISSUES, e.g., refund requests, technical bugs], and scaling support as the user base grows. Include best practices for maintaining a [CORE METRIC, e.g., CSAT score, NPS] while keeping costs lean. Provide real-world examples and avoid generic advice.