Animal Wellness Clinic of Tamarac review: Appointment deposit

I made an appointment to bring my cat in for a second opinion. I was told as the first time customer there would be a $50 fee that would be used towards the visit. I've never heard of such a thing but I still paid it. I canceled the appointment 8 days in advance and was told the $50 fee was non-refundable and was used to reserve the doctors time. I explained that I was disabled and on a fixed income and I was giving them eight days notice to fill the time slot but they still refused. I could understand if it was the day of the appointment or even the day before but they had over a week to fill the time slot. I feel this is greedy and unethical