Airtel — data booster auto renewal

Since my data plan got exhausted, i have taken booster pack, to my surprise its getting auto renewed every month without notifying.

I trust on airtel before this hence i was not checking the bill every month... But its a clear breach...

I have not expected this from airtel and when i called customer care, they said that it will not be reverted back..

What does a booster means? It is supposed to be an additional data recharge which should go off automatically next month...