Airtel Delhi — Threatening calls from Airtel

I had a phone no.[protected] with Airtel, Delhi, As I moved to other city, I canceled my connection. I also got an acknowledgement for my cancellation, but then after some days my friends and relatives started getting calls from Airtel saying that I havent paid my phone bill. When i tried calling that number, it was a board number and they never connected me to the concerned person.
Then, one day my parents got a call from someone mentioning that they HSBC bank (my bank) and have some urgent business totalk to me. She gave her phone number too. I talked to that lady, and then she says Madam I am not from HSBC, but I am from Airtel you havent paid your bill and even your phone is switched. When i told her saying that Icanceled my connection in April and if there is any bill due for me, please send me the details. She said she was sorry about the confusion and I wont be disturbed in future.
Now, again somebody called my sister mentioning that they are from my previous employer. They got my number and tried to harass me regarding bill payment.

I called up your call center and they mentioned that even though I
canceled my connection on April 17th, it was not done due to the
negligence on your end. They canceled the connection only in July and charged the May and June bill to me, which your database shows has not been paid to me. Now, the point is that though I have registered for e-bill, I never received any bill.

I wrote all this to Airtel and then again on 26th September, I got a call from Tees Hazari Court at 12:30 p.m., Delhi mentioning that some case has been filed against me and I have to be present in Court on that day before 2 p.m.

I told them i never got any notice and they said we gave it to your address and you were not there. I mentioned i was not staying in that address from last 6 months. Then they said whatever you do, its not my concern and you can talk to advocate Mr. A.K.Sharma on [protected].

When i talked to Mr. Sharma, he mentioned that i havent paid a bill worth Rs. 1693, then he mentioned that I should be in court before 2p.m. or else I will have to pay fine worth Rs.23, 000.
I told him I have already had many conversations with Airtel on this, and when they are not giving me any bill. how can i Pay it??
he is like i dont know what happened between you and Airtel, but if you dont pay this amount + rs.1100 as legal charges at Airtel Relationship center today before 2p.m., we will have to take further action.

I rushed to the Airtel Relationship center with just one hour to go, leaving my office work and in such mental stress.

These guys are criminals and they must pay for the harassment and defamation they caused to me.