Unfortunately, you evidently were aware of his policy about missed appointments: you certainly were aware after receiving and paying the first bill. If you missed appointments while being aware that you have to pay $25/each for missed appointments, then you are legally obligated to pay: in making appointments with this doctor while aware this is his policy, you implicitly agreed to it. It doesn't matter if you never missed appointments before this, or had good reasons for missing them, or were sterling patient, or refered other patients to him: all that legally matters is that if you are aware of the policy and make the appointment, you are boundy by the policy and must pay.