Consumer complaint against #Vodafone Mumbai

You won’t believe this. Vodafone Mumbai has threatened legal action against me for not paying for a number that I had already asked them to deactivate, after having cleared its dues and writing to them, and not having used it for a single day thereafter! And this to a customer who’s been with them for many years now, with three post-paid direct debit payment numbers. Any consumer guidance forums want to help?