FMLA FAQ – What if my employee’s doctor refuses to use our form?

We have requested a medical certification from an employee who is seeking FMLA leave. We have our own certification form, and gave the employee a copy. The employee came back with a form letter from the doctor’s office stating that they charge a fee for filling out FMLA certification forms, and a note from the doctor stating that the employee was injured and needed FMLA leave. Do we have to accept the note in lieu of our form?