Coserv electric Turned off service when paid Texas

 Paid my bill and i always pay over the phone and paid what it said i had to pay and three days later my service was disconnected.i called to find out why and they said i had a past due amount that was owed and they sent a separate bill. I said for almost ten years now i have paid my bill this way and now that you decide to send a separate bill i should have known. It was just another way for them to generate more money as i had to pay a reconnect fee. So it ruined my groceries and my poor dog that is very old was panting so bad but they didnt care, all they want is your money.