Airtel — poor voice & data service

Address:

Meerut, Uttar Pradesh, 250001

I m facing following problems with airtel network -
A) no internet -
1) when net is off - calls can be made
2) when net is on - network goes off and calls cannot be made and no internet also
Already changed the sim card to new (As directed by airtel customer care), but the issue is not resolved.

B) poor call connectivity (It takes 5-10 secs to start ringing)

Above issues are prevalent pan india for my number. Issues persisting since last 3-4 months, but no resolution has been provided.