Airtel — sim deactivation reg.

Address:

Chennai, Tamil Nadu, 600031

We would like to change some of our post-paid sim cards to pre-paid cards. Also, we have to get some of our sim cards blocked too. We request you to take swift action regarding this. Kindly do the needful.
We have already contacted one of your representatives, mr. Premkumar, regarding this. But, still, we didn't get any beneficial response from his side. Kindly give us a clarification on what we should do.