Airtel — daily international pack being activated without consent and without me activating it

Address:

Mumbai City, Maharashtra, 400020

Hello,
I was travelling to uk from 20th november 2018 to 8th december and as my relatives stay there, i was to use the local sim card throughout my stay there. However, being an airtel postpaid user, i never once did call airtel support or enquired about international roaming the same wasnt needed by me. It is pertinent to note that here, my airtel sim was not being used for a single day as throughout the trip, i was using the local card obtained by me in the uk.in the month of december 2018, after receiving the bill i was charged rs. 3894 excluding taxes for daily international roaming packs which they claim that i have used 6 times whereas i never activated these packs. How is it that without my consent or will that the service provider is activating services that are not requested/required or even asked for by me on my personal? And upon calling the customer care, everyone has a different answer to this but not one has the correct answer to this question.
?

This has caused a lot of problems for me because simcard has been deactivated by airtel, again for which answers are not clear. I have cleared the
Monthly rental which is to be paid every month because it is upon my consent that i activated the rental plan that i pay for but what is with the unauthorised activation of daily international roaming without my consent? This is clearly a way o[censored]surping wrongful gains from the customer.

Are service providers (Airtel in this case) really authorised to activate services that are not consented or asked/requested by the user?