It sounds like you may have a wage and hour claim against your employer, who from what I can tell is the the independent delivery company. You can contact the Wage Commissioner in San Francisco, CA, directly and file a claim. You should keep a log of the hours/times that you work and clarify your rate of pay with your employer as proof of the hours you work. If there are other co-workers in the same boat with you, you may want to file with the wage commissioner at the same time. The Wage Commissioner's information should be in the phone book. Definitely look for an attorney who practices wage and hour claims. There are time limitations for making wage and hour claims so don't delay.
If you receive a paycheck from one company, but another directs your daily activities, then you are probably in a joint employer situation where both are responsible for violations of the Labor Code's wage and hour laws.
Contact a lawyer who can direct your double attack.
Good luck to you.
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It sounds like there are multiple wage and hour violations here, and fortunately you are aware of them. California law presumes the employer is the entity on the pay stub; however in your case, if you are paid inappropriately by one employer while a second employer controls or directs your work, then both entities are your employer; this situation is called "joint employer."
The Division of Labor Standards Enforcement (DLSE) is a sub-agency within the California Department of Industrial Relations. http://www.dir.ca.gov/dlse/. Some people refer to the DLSE as the Labor Commissioner. The DLSE enforces California's wage and hour laws, including those pertaining to overtime, rest and meal breaks, and more. The link for information on filing a wage claim is here: http://www.dir.ca.gov/dlse/howtofilewageclaim.htm.
*** 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. ***