The plastic surgery clinic asks me to transfer the treatment fee to their bank account. Is it right for them to do so?

I went to a plastic surgery clinic for rhinitis surgery and nose surgery, and they told me I needed to have a CT scan, electrocardiogram, and blood test. I did as they asked and paid 60,000 won for the treatment fee. However, I received a bank transfer saying that 60,000 won was for the CT scan and that I had to pay another 100,000 won for the remaining tests. They said it would be different. Something was strange, so I paid by credit card instead of bank transfer and asked for a receipt for the medical expenses, but they said they wouldn't give me a receipt. Are all plastic surgeons like this? I went to 5 places for plastic surgery consultations, but this is the only place I've seen like this. It seems like a strange hospital, but I don't know where or how to inquire or report it.