My Doc Snuck In An Expensive Cancer Screener In My Lab Work. I Learned That She Gets A Commission. I Feel Tricked. Am I Legally Bound To This Bill Or Should I Fight It?

So I went to my doctor for my annual exam and asked for a pap and all the checks on my blood for hormones and health checks. After my pap, my doctor offered me a cancer screener from the company Grail. I asked if insurance covers it and she said that I could make payments on it every month. I replied, "I don't want it if my insurance isn't going to pay for it." She said that her lab assistant could help me with that information. The lab assistant who helped me told me that the doctor told her that I wanted the test. I told her that,"I don't want it if my insurance doesn't pay for it." She said,"Okay" and smiled before asking me to sign for several labs on my blood that the doctor ordered. The lab assistant gave me told me that Grail would contact me about fees. I figured that this meant that they would let me know fees and information somehow to get this done. Later after time, I received an email with an attachment that I opened that had cancer screening results and a $900 bill. After contacting them, their local representative, the lab assistants, the lab they worked for, and then the doctor, I finally got answers. The representative from Grail told me that the doctor's office receives a commission for every test they conduct and reminds the lab technicians to ensure that they ask clients before conducting the test if they agree to receive it. I did not agree. Grail keeps sending bills and says that they can't do anything about the bill I now owe. My doctor told me that I signed paperwork to have the test done, she remembers that I had initially told her that I wanted all the checks on my blood and that I can surely pay $30 a month for this test. I told her that I had told 2 medical professionals that I did not want the test and that I signed for my blood tests, not that one. I also told her that the lab assistant did not explain anything to me and that I didn't want another medical bill because I have other medical bills I pay every month. She said that no other client has complained and that all her clients are fully explained the test. I told her that I hadn't explained anything and that I must have slipped through her process. She let me know that I signed for it and that I was responsible for it. I feel tricked. Is she correct? I thought about filing with a small claims court. Does anyone know if I have a case that could win to give her the responsibility for this bill?