Airtel — not re-activating my pre-paid sim in grace period

Address:

Bangalore, Karnataka, 560037

Hi
My Airtel number got deactivated on 25th September 2018. I know why it got deactivated because it wasn't used for a certain amount of time. I mailed airtel guys to reactivate it. They said you have grace period of 15 days and you can send your blood relative to the airtel store with your original documents. My sister went to the Karthik Nagar Airtel store Marathahalli Bangalore only to find out that airtel representatives in the store are denying to reactivate. On asking why, they simply said - "Mam we want an email from airtel customer care saying that they have allowed us to re-activate and that you are the authorized person". I then mailed the airtel customer care and the nodal officer telling them that my sister went to a store and such things happened. I requested them to send the authorization email to the store in which they have also authorized the person(my sister). To this they are responded every singe time with this email :
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"Dear,
Greetings from Airtel!

This is in reference to your email regarding services not working for your airtel mobile number xxxxxxxxx.
At the outset, we regret the inconvenience caused to you.
We would like to inform you that services for your airtel mobile were discontinued on[protected] due to no usage found on your number in last 90 days. Usage could be with respect to
an outgoing call, SMS or data usage. Beyond 90 days period, in case of no usage, charges of Rs.20/- per month are deducted from main account towards service extension for 30 days.

Due to insufficient balance, the amount could not be deducted and services were disconnected permanently.
Further, you may get the same number reactivated within grace period of 15 days from the date of disconnection by paying reactivation charge of Rs.20/- at airtel relationship Centre in home circle.

We request you to visit airtel store any of your blood relative (Father or Mother or Brother or Sister) along with the documents to reactivate the SIM in home circle only.

For your convenience, we are including airtel store details URL which will help you to get nearby store http://www.airtel.in/forme/arc/reach-airtel

Thanks for reaching out to us. Delighted to assist you!"
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How is this assistance and not harassment. Every-time I tell the airtel guys that my sister(a blood relative) went for re-activation and every time the store manager denies reactivation. Still the airtel customer care instead of helping me is sending this unnecessary answer. Why are they not sending the email to the store for authorizing the store and the person(my sister). This is ridiculous.