How to write a warning letter if the employee is late 13 times a month?

Enterprises or units should have rules and regulations about being late. Since they make mistakes again and again, they can make full use of existing rules and regulations to punish employees who make mistakes. If they don't, it's not too late to do it now. Only by using system administrators and binding personnel can we really improve efficiency. No matter how good the warning letter is, it is not as useful as a perfect system.