Charging Bill without Service

&lt;p&gt;&lt;b&gt;Location/place&lt;/b&gt;: gd 67, sec-3, salt lake city, kolkata-700106&lt;/p&gt;<p><b>Name of company/service</b>: tata docomo(photon)</p>I had a tata photon plus internet connection. When I buy it from their head office they assured about after sale service. After 3months from purchasing I faced massive ‘low tower’ error on my device. Instead of 173kbps I received only 10-15kbps or no receiving at all. So I launched a complaint. No body has come. I take some screen shots as a proof. After a few days I stop using the modem because it was useless. I also stop payment because of avoidable tendency of company. After a few month certainly they woke up and send me a legal notice to clear the bill. I asked them to come to my home. They didn’t. Since then the company continuously threatening me over phone. Company appointed lawyer Arun Mishra(as he said over ph) threat me with an offensive language. Now I want to launch a case against them. Advice me.