Money has taken without giving connection

Location/place: Chennai

Name of company/service: Airtel / Broadband Connection

I have given a request for broadband connection to Airtel 2 weeks back (Jul 4). They have taken the request with cheque for Rs 999.00. I was following with them for the connection but, so far there is no response from them. The cheque got cleared a week back (Jul 18) but still there is no response from them to provide the connection.
Please let me know the procedure to file suite against them.