Vodafone And Idea VI - Vi store extorted money from me

I have been a vodafone idea customer for the last * years and I had a prepaid sim in my name, a month ago my sim stopped working so I went to a vodafone ministore(Sector *, near city center, Kolkata-******) that is near to me for replacement, instead of replacing my sim with existing prepaid sim they gave me a postpaid sim in my name without my permission.When I got a call for postpaid verification, I was stunned and I told the rep who called me that I never applied for any postpaid plan. Naturally my sim was suspended and I went back to vi store when questioned they said vodafone stopped prepaid services entirely(lie) and I have to pay *** every month for postpaid,but I really needed my phone number urgently for some bank related task so I gave in and paid them ***rs to start the line(extortion), I tried calling vodafone customer service many times but received no help,a complaint has been lodged but I have lost *** rs because vodafone incentivises their store executives only if they sell postpaid connection,which leads to them lying and using predatory sales tactics on customers.