Provide an option to report errors
On the top menu have a "report a problem" option. When a system error opccurs it is extremely difficult to inform you about it, you should make it easier for customers to help you. They face a problem, they report the problem immediately, it is logged and you monitor the logs and take action. Your Status Page show everything fine yet I am unable to process payment, I go to down detector and find others have same problem... this should be visible in the site and customers will make life easier for you and visibility of issues makes it easier for customers.