Being harassed by Docomo for incorrect bill amount post disconnection of service

Hi, I had a broadband connection from tata docomo, my tataphoton no being 976. I am being harassed by the company and its lawyers after I had requested for a cancellation of their services. My bill cycle ended of 28th of every month. I submitted my request for permanent cancellation of the connection on 24th december ( 4 days before the end of the billing cycle) and had paid the entire amount due for this billing cycle in advance on 30th november . (I have email confirmations to all these) however, these guys ( tata docomo people) kept on calling me for an entire two weeks, asking me to take another plan or get the line transfered to another name and all such similar crap but not to get the service terminated, the result being that my connection finally got disconnected on 9th jan and since then they have been after me to pay the rentals for the next billing cycle as well. I have explained all these sequence of facts to the company representative, every time they used to call me for paying the balance money as well as have also replied to the emails of their legal advicer "in curia law chambers" but I have been continously receiving email legal notices from them. It seems as if they have set up a rule in their outlook, which fires an email every month, without bothering to check my replies. This not being the end, I was astonished to see another letter from them today, asking me to attend a lok adalat for settling this dispute amicably. I do not understand why do companies like tata have to resort to such unethical behaviour when it comes to cancellation of their connection. I would request for some help in lettting these companies know that they cannot unilatterly play tantrums with the consumers when it comes to disconnection ofservices and would want to sue them for harassing me like this. Regards pankaj