Which customers have used both the service named "Close a policy" and the service named "Upgrade a policy"? Give me the customer names.
select t1.customer_name from customers as t1 join first_notification_of_loss as t2 on t1.customer_id = t2.customer_id join services as t3 on t2.service_id = t3.service_id where t3.service_name = "Close a policy" intersect select t1.customer_name from customers as t1 join first_notification_of_loss as t2 on t1.customer_id = t2.customer_id join services as t3 on t2.service_id = t3.service_id where t3.service_name = "New policy application"