Airtel — Number Reissue

My number has been reissued to someone else. I have been a loyal customer for almost 6 continuous years.

I couldn't recharge my sim for 3-4 months for some reason. But I still I was using that number on WhatsApp and other social media. When my friends told me somebody else picked up the call, only then I realised that my number is given to somebody else. Neither your customer care nor the Digboi Airtel office could be of any help as the number is not registered to me anymore. They said all I can do now is try to convince the person to surrender his sim which is hardly a week old. Now the thing is I need my number back which is linked to my Google account and social media. Thank God it wasn't linked to my Bank. If that person wants he can take control of my data. Just an OTP away.
See deactivating my number is fine. I understand all that. But how on earth do you take my number and give it to somebody else?

I want my number back. My female friends who called that number thinking that's me get multiple callbacks despite them telling me it's a wrong number and it's low-key harassment. One of them got 20 missed calls. I want this resolved. If harassment further continues I will file an FIR against the sim holder and the sim issuer that'll be you.
Just give me back my number safely before things turn ugly.