Indian Oil Corporation [IOC] — extra delivery charges.

Address:

Kolkata, West Bengal, 700064

I have an indane connection. Few days back when i was receiving a gas delivery the person asked for extra delivery charge and threatened to take the gas away if i didn't pay.
So i had to pay him extra.
He also said that next time i will keep the gas on the main gate and not deliver it to my 1st floor if i don't pay 30 rs extra.
Can i get some help?
I want the agency to tell the delivery men not to ask for more money and to be polite. They threaten that call the agency but nothing will happen and next time we will not deliver or show fake delivery done.