Vodafone — BIlling

I have been relocated outside of India and I have requested to terminate my other vodafone number [protected]. As per the representative, Shayani Srimani, I have cleared the due amounts and she has also provied me the closure letter for the same and she has specifically mentioned that my number got suspended and there is not such due amount I which I have to pay. But now again a bill of 66 Rs has been generated. Why this is so? I have contacted her and she mentioned that I wont have to pay that amount but I would like to know that why it has been generated?