Unless you have some employer policy that would otherwise allow you to keep the seniority point, it is not unlawful for an employer to do as you have stated. Just the same as an employer is not required to keep you on medical insurance or keep paying you when you are off on a disability, it is not required to continue to have you accruing seniority as well.
Also, there is no such thing as an ADA that you can call. The EEOC administers and enforces the ADA. The Department of Fair Employment and Housing administers the Fair Employment and Housing Act, the CA law that more protectively covers disabled employees.
Good luck to you.
This answer should not be construed to create any attorney-client relationship. Such a relationship can be formed only through the mutual execution of an attorney-client agreement. The answer given is based on the extremely limited facts provided and the proper course of action might change significantly with the introduction of other facts. All who read this answer should not rely on the answer to govern their conduct. Please seek the advice of competent counsel after disclosing all facts to that attorney. This answer is intended for California residents only. The answering party is only licensed to practice in the State of California.
Mr. Pedersen is correct. No employer has to continue seniority accrual for employees if it is based on hours worked. That said, if you were or are able to work more hours than you have been with a reasonable accommodation (some adjustment to the way in which you perform your job, or some redistribution of certain duties to other employees), you should speak with an attorney who can assist you in determining if your employer should have provided you with reasonable accommodation in the past, or if you are entitled to reasonable accommodation now and into the future.
To find a plaintiffs employment attorney in California, please go to the web site of the California Employment Lawyers Association (CELA). CELA is the largest and most influential bar association in the state for attorneys who represent working people. The web site is www.cela.org. Click on "Find a CELA Member" and you can search by location and practice area. Many CELA attorneys represent clients throughout the state.
I hope you can resolve your situation and wish you the best.
@MikaSpencer * * * twitter.com/MikaSpencer * * * PLEASE READ: All legal actions have time limits, called statutes of limitation. If you miss the deadline for filing your claim, you will lose the opportunity to pursue your case. Please consult with an experienced employment attorney as soon as possible to better preserve your rights. * * * Marilynn Mika Spencer provides information on Avvo as a service to the public, primarily when general information may be of assistance. Avvo is not an appropriate forum for an in-depth response or a detailed analysis. These comments are for information only and should not be considered legal advice. Legal advice must pertain to specific, detailed facts. * * * No attorney-client relationship is created based on this information exchange. * * * Marilynn Mika Spencer is licensed to practice law before all state and federal courts in California and can appear before administrative agencies throughout the country. She is eligible to represent clients in other states on a pro hac vice basis.