West Bengal State Electricity Distribution Company [WBSEDCL] — Application for falsely charged fine

Address:

Ragunathganj, murshidaabad, West Bengal

I had given the electricity bill of my house and our neighbors house via gpay on 22nd march. My payment was successful as it was received by wbsedcl which is present as a proof in my bank account passbook and in gpay app . I have the upi transaction id of that very payment. Now in this month they sent us current electricity bill with fine of previous bills amout as according to them they refunded me the amount after some days of my successful payment which was not even notified to me.
My question is I had paid within the given time but why should I pay the fine?