Service tax on foreign remittance to booking.com against commission

Dear,
Sir
Service tax department demanding service tax on the part of commission that i have remitted to Booking.com as commission for booking my hotels.

Booking.com charging commission from me for booking my hotel @ 15%, and service tax department demanding commission on this 15% part.

Booking.com have not any permanent establishment in india.

Booking.com have Double Taxation Avoidance agreement with the Republic of India

I have already deposited service tax on the part of room charge that I charged from our customer.

Sir kindly help me about this should i pay service tax on this part or not.

Sir Please Advised me as early as possible.

Thanking you in Anticipation.