Tata Photon Plus — Extra bills

Address:

North 24 Parganas, West Bengal

I was using Tata Photon plus postpaid connection .I used that net connection last on June , 2011 .After that as i was not satisfied with the connection , i thought of discontinuing that connection .i called the customer care and told him that i wish to disconnect .Then next month again the bill came and they gave the reason that i told them to discontinue after 12th march which is my bill generation date. So i need to pay that.That month i paid the bill simply without using the net at all and paid the amount to a guy who used to come to collect from home.i told him also to disconnect from next month.He told that he will do.Now next month again the bill came.i didn't bother to pay .After 3 months 1 guy came to our house and told my bills are pending from 3 months.I told him all the story and after hearing all this he told that he will look into the matter and discontinue and we paid the bill for 3months again .
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NOTE:Till this point no-one didn't even tell me to send a mail or any official letter to disconnect .After this again bill started coming.Again after 3 months some guy came to collect and he told to do the official things.My question is why no-one told me about this before and i paid some 4 months bill without using this at all.And when i paid all this and telling them to discontinue why they are not disconnecting.It has been almost a year .Now they sent some advocate letter to pay the bill otherwise they will take other actions against me?????
why they harass people so much??
After paying 4months of bill , i am not feeling to send any official letter to them .When i am not using that and not paying the bill why they are not disconnecting ????????????