Service tax for franchise in education industry

Hi All,

I have a query regarding Service Tax for franchises in Education Tuition Space. My Company (A) had taken a franchise of a tuition firm  (B). All the revenue was collected by (B) and they would pay the service tax on the entire amount. On the remaining amount, they would caclulate our share and give (A) the amount accordingly. As a result, we did not pay any Service Tax. Now we have received a mail from the Service Tax department asking why (B) has not paid any Service Tax. How to reply to the mail from Service Tax department?  

Any help on this will be appreciated.