This what the California licensing handbook has to say about this situation:
Steps to Take if Your Supervisor Will Not Complete a Certificate of Experience
If your supervisor refuses to complete a Certificate of Experience on your behalf, the
CBA recommends you take the following steps:
1. Submit a written request to your supervisor asking that he or she complete
the Certificate of Experience on your behalf, and submit a copy to the CBA.
Your request should provide the supervisor with a reasonable amount of time
to respond. It is suggested that all correspondence be sent Certified Mail,
Return Receipt Requested.
2. If your supervisor does not respond, a follow-up request in writing should be
made.
3. If your supervisor still does not respond, and you have filed your application
with the CBA, you may submit a letter requesting that the CBA assist you.
Copies of the original and follow-up letters should accompany your request.
Once the above steps have been completed, the CBA will contact the supervisor and
request submission of a written explanation regarding their refusal to complete and
submit the Certificate of Experience on your behalf. The supervisor will be notified that
any individual, whether or not they have filed an application for licensure with the CBA,
has the right to file a complaint if they believe their supervisor is impeding them from
becoming licensed.
Under the provisions of CBA Regulations section 69, if you believe that your supervisor
has willfully failed or refused to complete and submit a Certificate of Experience on your
behalf, you may file a complaint with the CBA Enforcement Division. Instructions for
filing a complaint may be obtained by contacting the Enforcement Division by email at
enforcementinfo@cba.ca.gov or by telephone at (916) 561-1729. Once the complaint is
filed, the CBA will investigate why the California CPA has refused to provide a
Certificate of Experience for experience obtained under his or her supervision.