Do anyone know what is the right wording for a employee changes the dates on his medical certificate

We phoned the doctor and he only gave him one day of but the employee change the date to 3 days.
He never phoned in to let us know he is not coming in to work
the doctor will give us a report with the right dates on his certificate

What is the right way to handle this matter it is the first time I have to deal with this sort of problem

Normally it only bad time keeping

thanks