Vodafone And Idea VI - Harrasment by Vodafone and Forcing to pay Overpriced Bill

I have been using the same number for over * years have the same bill every month and I have been paying it religiously Every month. When Vodafone changed to "VI" I had *** GB of data in my account which was a rollover from couple of previous months. Suddenly over night my *** data disappeared from my account and Where I would usually get a bill of *** i was sent a bill of ****/-.. i was shocked looking at this bill so I contacted customer care and explained my situation. They said they are looking into the matter... Then I call them again to follow up and they ask me to contact different departments which I did. They raise a complaint about my issue and I wait for it to get resolved.. by this time They have blocked my number and then multiple recovery agents started harrassing me on Whatsapp and i told everyone the same thing everytime that I am waiting to get my issue resolved and without any communication or anything they have decided to do whatever comes to their mind.. i refuse to pay the amount they have charged and agreed to pay my monthly bill alone of ***. They refused said u have used all of this then you have to pay ... Like this is the customer service to expect after using vodafone for over ** years in my life... Then they started sending me discounts on my bill of *%, **% etc which went upto **% discount... my question is if you were sooo stuck on saying that i have to pay for what I have used then why offer these discounts? Now I am receiving a notice from Lok Adalat on behalf of Vodafone.. please help me as to what to do in this matter !