Refused to refund rental cost for defective steam cleaner

My experience with this store was very negative. I rented a steam cleaner from Envirowise in September 2012 to clean my carpets. After I got it home and filled it with the cleaning solution, I discovered the pump that sprays the water didn't work. I called the store and the employee gave me her manager's number (Carol Waters). When I explained the problem, Carol said it had happened before and that when I returned the machine they would refund my money. However, when I took the machine back, I got a different story: Carol wanted to have the machine checked by a technician, and if he found it didn't work, then she'd give me a refund. I called her to say that I expected my money back regardless of whether it worked for the technician, since it hadn't worked for me. She said she'd call back, and I never heard from her again. I wrote a letter of complaint and asked her again to stick to her word and refund my rental, and I still have not heard anything. I am appalled by this lack of integrity in a business person and although I like Envirowise's environmental orientation, I would recommend not patronizing this business because of its manager's lack of ethics.