Airtel — regarding the landline connection

Address:

Hyderabad, Andhra Pradesh, 500033

I was called over phone by few people, from airtel broad band line connection for installation.
I accepted to upgrade from ll [protected]. There were couple of people who called continuously and check my address around 30 times and no one has come installation.
There was a threat from airtel people. As on request i didn't give any complaint and they have removed the connection. Its almost four months now they are sending rs.1500 amount due.

Can i know the amount claiming is right, i would launch official complaint on this as they abruptly remove connection in middle of month and claiming the amount.
I would like to know whether i have to pay all amount and keep quiet or shall i fight

Regards
P. Dharmanandan
[protected]