Airtel — data logging error

I use Airtel Broadband in Pune. In Nov-19 and Dec-19 during the normal billing cycle period, I got 50% data consumed message and I was totally surprised. I just have a PC & mobile and no other device, no other user and I never had so much of consumption.

I found significant uploads data logged as my usage under my account.
I complained to Airtel. They did not provide any answer to my complaint and provided no answer even after 10 days. Rather they said there can not be any complaint for data consumption.

Something is fishy at Airtel end which they are not ready to share. Users are requested to be alert and daily check their usage against their account on Airtel website to be sure that there's no data logging mistake on part of Airtel.