You are an operation manager in a retail chain, and your assistant just handled you with this quarters report. 70% customer satisfaction rate is a big shock for you, which has lowered 10% by comparing with last quarter. By checking with the sales revenue, it also had a 10% decrease. You have to write the report to your boss next week. Please discuss the steps or procures of how you can verify the issue (s). And provide a solution, how you can monitor and control. (Please note that the answer must match your main problem)