First, unless you have a contract defining your job or duties, then your employere is free to have to do work outside your job description or for which you were not hired. Without a contract, you're an employee at will, and employers may alter the terms, conditions, compensation, hours, etc. at will of employees at will--or terminate them at will.Second, unless you are being discriminated against on the basis of a protected characteristic, such as age over 40, sex, race, religion, or disability, your employer does not need to pay you the same as other employees doinng the same job. There is no legal requirement to generally treat employees fairly.