Instead of attacking the employee for not making changes to her work behavior, simply state that since the issues still exist, a warning letter is necessary.

A Guide to Writing Employee Warning Letters For Any Scenario Subtle hints not cutting it? It may be time to formally address your employee’s performance issue with a written warning.

How a Write a Warning Letter for Employee Conduct When employee behavior or poor performance don't shape up after verbal warnings, its time to get formal. Here's how to do it right.

Ask if your company has a no-call/no-show write-up sample. You might ask other managers to an example of a write-up for no-call/no-show they've written in the past.