How to send a legal notice without knowing address?

I started taking private tuitions for singing from an independent teacher. The teacher asked for the payment for the classes to be made before the start of every new monthly session. The classes used to take place for 2 days per week, with around 3-4 days gap between each class. I made the payment for the next monthly session in advance, as required by the teacher, but due to some recent circumstances, I'm unwilling to continue for the next session. I haven't attended a single class for the new session, but the teacher has refused to refund me the fees amount. I wish to file a complaint to the consumer court but before that I need to send a legal notice to the person. Kindly advice me how should I send the notice without knowing the residential address of the teacher. I know the address of one institute where this teacher is employed. Please also advice me whether I have a valid cause, and whether it will be entertained in the court. Thank you