Consumer Redressal

sir/mam i have used MTS Mblaze dongle for 2 years. i requested a disconnection in December, 2011 due to interrupted services, misguidance by customer center and customer helpline no. i filed a lots of complaints threw phone, by visiting there customer center also by emailing there nodal officer email id provided on the mts India website, but didn\'t got any response. Now its been 15 months and they are calling me and messaging me and harassing for non payment for bill for 3 months. i.e approx Rs 3000. i only didn\'t paid the bill for Nov, 2011 i.e approx Rs 990 because when i went with a complaint on there service center they gave me a new dongle for Rs 750 in replacement of old one which was not working and they didn\'t activate the new device for 2 months even after my 50 calls and 10 visits to there customer center which is very far from my house, also they emailed me a FAKE LEGAL NOTICE. and called me twice saying they are calling from DELHI POLICE and they are filing a case. Advise