7837779895: Stopped working

Dear Sir

As the email trail mentions, I am currently living in the US. I am an Airtel user for some years and my phone number is +91783 777 9895 which is not working. I visited India in Jan-April 2018 and left for the US on 9 April. I was working until the last two weeks. I recharged it for Rs 400. I logged into my account and checked it has a balance of Rs 107.

I email to the Airtel to ask why it is not working and how it can start working. It is important as this phone number is connected to my Indian bank account and I am unable to get an OTP. In the reply they sent me the following emails:

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Dear Customer,

This email ID is not registered against Airtel number 7837779895. Click Here to authenticate your account and help us process your request.
If your query is related to some other number, please mention that number in subject line and reply to this mail.

Warm Regards,
Bharti Airtel Ltd.
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My phone is not working, how can I get the OTP to authenticate the request they have sent. I sent them a screen shot of my login page that shows that my email is connected to my Phone number.

How I can get an OTP on my phone which is not working?

Please help me getting my phone started again.

Best regards