Q: I believe my employer is taking advantage of me. This company hired me to do telephone sales as an independent contractor, which means that I am paid strictly on commission with no benefits. There are no other contractors in the office where I am located.

My problem is that the office supervisor keeps giving me additional tasks. She frequently tells me to order supplies, make travel arrangements or answer the phone. These activities interfere with my sales calls, and I receive no pay for doing them. I'm usually a cheerful person, but now I feel irritated all the time. What's your advice?

A: If your company has a human resources department, that's where this problem belongs. "Independent contractor" has a specific legal definition, which may never have been explained to this supervisor. The HR manager should be able to educate her about the limits of your work activities.

On the other hand, if this is a very small business, you may need to address the problem directly. To reduce your irritation, try making the reasonable assumption that the supervisor simply doesn't understand your circumstances.

For example: "Mary, I need to talk with you about how I'm spending my time. Because I was hired as a contractor, I only get paid when I make a sale. Unfortunately, I now seem to be involved in a lot of unpaid activities. Although I want to be helpful, I really need to start focusing on my sales calls."

After that, when the supervisor approaches you about an extra task, indicate that you have many calls to make and ask if someone else could handle it. Just be sure to explain your unique payroll status to your co-workers. Otherwise, they might logically assume that you are trying to avoid work.

Q: One of my colleagues keeps taking files from my office without permission. I manage a school health room where we have medical records on every student. Whenever someone is transferring to another school, the secretary walks down to my office and gets the medical file, even if I am not there.

Before these records are sent elsewhere, I need to review them to be sure the information is up to date. I have asked the secretary for some advance notice, but she continues to take files without telling me. This is driving me absolutely crazy. How can I stop her?

A: That's simple. Lock the file cabinet. Because health records should always be protected from prying eyes, this action will be easy to explain. If the current cabinet has no lock, you have a legitimate reason for requesting a new one. Give your boss a key, along with a warning that the secretary might complain.

When your intrusive co-worker inquires about this change, explain the need for security and assure her that you will provide requested files within 24 hours. This is just another example of how confrontations can sometimes be avoided by focusing on business needs instead of interpersonal irritations.

Marie G. McIntyre is a workplace coach and the author of "Secrets to Winning at Office Politics." Send in questions and get free coaching tips at www.yourofficecoach.com or follow her on Twitter @officecoach