It Pays to Speak German (literally)

When I go see a doctor here, I usually start out using German, and see if I can make it through the appointment without one of us feeling the need to switch to English. With one doctor I've been seeing regularly for 4 years now, and who can speak perfect English, we now converse in German. When we started he would always start in German, and then only switch when I would ask. Eventually I had enough confidence not to feel the need to ask.
Sometimes when I'm seeing new doctors, like I have been recently for some sort of nagging adductor tendinitis - groin pull - I start in German, but a combination of not understanding new technical medical words in German and wanting to make sure I'm perfectly clear about what the doctors are saying leads us to switch to English. I would say 3 of 4 doctors I see can speak English much better than I can German. Even the ones that can't speak English well make a good-hearted attempt, and I appreciate that, and we try to work out the technical jargon between us.
In many ways it's fun for me to make it through an appointment without having to switch to English. Gives me a boost to start my day. But I never in my dreams thought it would be financially beneficial. Until now. I was just opening doctor bills and going through charges, and I cam across one from a new doctor that I'd never seen before. Under it, it reads:

"Begründung: sprächliche Verständigungsschwerichkeiten: Anwendung Zweitsprache Englisch"

And then a charge of 17 euros. The above says the reason for the charge is there were difficulties in understanding and the doctor had to change and use a second language, English.
I'm seriously dumbfounded. Especially since the rest of the charges amounted to 75 euros, basically for this doctor to tell me after 15 minutes I needed to see a different doctor. He didn't tell me when we were 3/4 the way through the appointment that when I asked to clarify something by describing it in English it would cost me 20 bucks.
Doctor H. Witzigmann of the Friedrichstadt Krankenhaus, a true winner.
Again, never in 4 years have I ever seen this charge on a doctor bill.