"Rude and humiliating telephone manner"

I rang the BMI Referral Management Centre to rearrange my NHS appointment, the receptionist was extremely rude and raised their voice like I was incapable to understand basic English. I was also not given time to decide which date and time I should book. The time slots offered were very limited so I had to choose the least inconvenience one. Then they said " Now you can do (the date)?" 10 minutes wasted and nothing done, I have never been so humiliated before, I am going to another private hospital rather than going through the whole rubbish experience again.