Student or Learner
We would like to take this opportunity to introduce our ad agency, xyz, an INS accredited agency. We are gateway for all the communication needs, we provide cost effective & result oriented efficient solutions. Enclosed herewith are two CDs – agency profile & TVC commercials created by us for your reference.
Awaiting your positive reply
It depends on how friendly/intrusive you want to be:
We are a gateway for all communication needs ... Objective
We are the gateway for all your communication needs ... This is a more modern, trendy way of saying it. You are asserting that you are the right company for them.
Having said that, I don't like the ending, "Awaiting your positive reply"
You'll have to decide which style works best in India.