GST on commission charged for booking tickets of a bus operator.

In my opinion- GST will be charged as the service provided by you to bus operator is a kind of support service to business or commerce. further, it comes under classification of support service to passenger transport service by road.
The exact SAC is under heading 9985 sl no. (i) supply of tour operator service and attract gst @ 5 percent.
the bus operator is giving wholly exempted supply hence as per provisions of sec 17 - he is not allowed to take credit hence not alowwed to take refund under act