I assume you mean you contacted your employer and you are the employee. California law requires that employers provide its employees with pay stubs containing specific information about their pay, including their pay rate. Wages are determined by agreement, whether verbally or in writing. Employers cannot simply arbitrarily decide how much they wish to pay you from one pay period to another. If your employer refuses to commit to a rate of pay or you believe it is not complying with California law, you should seek the assistance of an employment law attorney for advice and direction.
They say you get what you pay for, and this response is free, so take it for what it is worth. This is my opinion based on very limited information. My opinion should not be taken as legal advice. For true advice, we would require a confidential consultation where I would ask you questions and get your complete story. This is a public forum, so remember, nothing here is confidential. Nor am I your attorney. I do not know who you are and you have not hired me to provide any legal service. To do so would require us to meet and sign written retainer agreement. My responses are intended for general information only.
Your question is a bit ambiguous. If you work by the hour, you should know before you do the work what your hourly rate will be. If you are in a piecework job, you should know the amount per piece you will receive. The employer can change the numbers at its will as long as the number does not fall below the minimum wage, but the change must be prospective, meaning from the point of notice of the change on.
If your hourly rate varies because you are on a commission or piece rate basis for determining your wages, it would make sense that an hourly rate is not stated. However, that would not relieve the employer from having the basis for the pay stated on the stub.
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.