Airtel — disconnection of my postpaid number without any intimation.

I had a post paid number which was kept under safe custody with Airtel India. The account had enough money to keep the number under safe custody for a long time but somehow Airtel decided to disconnect the number with any informing me about it.
I have been trying to get Airtel to get me my number back as I had that number for more than 10 years and most of my contacts know that number. Airtel’s email reply are so bad that, no one reads the emails and keeps telling me to come to a store to get a new number.
Airtel customer support has been worse, they never call me back, I have spent more than 4000 Rs in the last two months to get some information about why the number was disconnected and how to get it back. Each time they need 48 hours to get back to me but they never do actually get back. I have to call them again and then they again ask for 48 hours. Most of the times their support has tried to blame me for this disconnection (which is not the case). I have been told the following,
1. You took it out of safe custody (reading an email from last to last year).
2. You have not been using the phone. (A phone under safe custody can’t be used)
3. There was no money on the account. (It had credit on the it and it was disconnected after which they have supposedly sent me that money back via check, which I can’t confirm as I am not in India. Also I never asked them to do so, that money was to keep the safe custody in play).
4. One guy told me that I have to send them an email every month to keep it in safe custody (I was never notified of any such policy change, I used to turn on the safe custody and keep it on till I wanted to use the number).

Airtel social media services are another place where I tried. Let me tell you these guys are even worse. They don’t read any messages and also laugh at you when you are trying to explain them your problem. They asked me to send a family member to Delhi store to just check the availability of the number (which somehow the customer care can not do internally). When I did send someone to the store, the store told my family that the number is with Vodafone now (it was ported from Vodafone). When they visited to Vodafone, they confirmed that Airtel has still not sent the number back. Now they both are making my family run around in stores just because Airtel does not care about their customers.