Airtel — new airtel connection but number not provided as committed

Address:

Kolkata, West Bengal, 700012

This is to inform you that the new connection from airtel was installated at our office which is still not functioning. The number which was allotted to us, the same was not provided after installation, it's been a month now no one has come to give us the new number. The router is lying switched off and we have not even used a single day.
We sent email to customer care [protected]@in. Airtel.in but there is no proper response, we guess they are just not interested to solve the issue and are least bothered.
But must admit that airtel was best few years ago and now it's becoming night mare to deal with them.