Vodafone India — incorrect billing/ system issue

Address:

Mumbai City, Maharashtra, 400101

I travelled abroad in the month of june 2017, vodafone activated my international roaming without my consent or request. (As per them it was pre-activated from 2016 when i travelled to another country). I did not intend to or use their services. Despite that they sent me bill for over 34000 all for data usage. I had a local number while i was on roaming, clearly there was not a single call or message made or sent from my vodafone number. At most places in todays time data if free at hotels, buses, airports etc. So it does not make any logical sense to have this kind of a bill. Another discrepancy is that my average monthly bill is rs. 1000/- however vodafone has assigned me credit limit of 27000 (Note that customer does not have any control over this) and despite them setting credit limit of 27000, my bill amount for the month is 34000+ ; what does that even mean?
I wrote /called them numerous times but like robots they just keep repeating themselves and when asked speciifc questions on their systems they stopped responding to me.
I had also made a port out request to them which they have not actioned.
Please advise what can i do as a consumer to deal with such pathetic service standards..