Bharat Sanchar Nigam [BSNL] — receiving bill even after submitting disconnection letter

Hi,
On march 16, i've submitted a disconnection letter to bsnl office in mavelikara. They checked the account, as it was 700 rupees deposit, he told me to bring the passbook attached which i did and he said it will processed within 1 week. We were out of town for 3 months, and when i reached home and checked the phone sms there was a message from the bsnl that pay the pending bill.
I don't know how careless they are as i’ve submitted the request 4 month ago

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