massage therapist has a question about payment

[STACIEB]

I am an Independent Contractor at a day spa. I am a Massage Therapist. The owner of the spa is discounting packages and i am getting a percentage of the price of the discount instead of the full price of the service. This happens all the time. Recently a client brought a gift certificate in of the amount of 100.00. I performed a massage that costs 95.00. The owner is paying me a percentage on 81.00.When i asked her why it was 81 instead of 95 she said that the gift certificate was purchased thru a website that advertises her business and it costs 17 dollars each time someone brings a gift certificate in from that website.I then asked her how she felt about increasing my percentage for that massage because it was discounted so much and she said no, because she is doing all the marketing. I feel that i should get a percentage of the price of the service thats on the spa menu, not a discounted price. I supply evrything except the massage table and I even book appointments and check clients in and out because we have no receptionist anymore. I pay my own taxes and am supposed to be an independent contractor.does being an independent contractor mean I have to accept what she is doing? Or can I tell her I want the full amount and she eats the discount? Help! Thanks