Yes, you are being exploited. But unfortunately, it's not even remotely illegal to exploit employees. Employers have 100% discretion as to what duties to require employees to perform how many hours they have to work subject only to paying nonexempt employees overtime as applicable and paying hourly employees for all hours worked what responsibilities, titles, and authority to give employees whether to make a position permanent, temporary, acting, etc. whether and when to promote whether, when, and how much to give as a raise. So your employer can keep you as an "acting" manager for forever, without an official promotion or any pay raise.