My 10 yr old daughter attends the Ballettschule Kleinmachnow on Hohe Kiefer, near the Lidl. If you've driven along that way, you can't miss it - the pink house. She is not a German speaker but has been happy there for about 6 months now. The same people also manage the Ballettshule on Lindenthaler Allee, but I don't know if it is the same instructor. The teacher speaks some basic English, although the lesson is conducted in German.
You can have a couple of free trial lessons to gauge which class is best for your daughter and whether she likes the place. After that, it is a monthly cost (Eur 40). The best way to find out about it is to pop in and pick up the leaflets (As seems to be usual here in germany, the website is not very helpful-
http://www.ballettakademie.de/ -), the teacher normally has a couple of minutes spare at the beginning and end of each lesson to talk (I can confirm that happens on the Thursday lesson at 5 & 6 pm). She was fine with my daughter's lack of German and has since said that she is pleased with the progress, so the language does not seem to be a barrier. If you decide that you do like the place, there is no pressure to immediately buy all the uniform, so you can then confirm that things are going well before shelling out (Things aren't cheap here - we ended paying Eur 69 for the dress, although H&M do cheap shoes and tights).
Let me know if you need any more info.