I have a Condo in Bang Na and my Electric bills are from the (MEA) Metropolitan Electricity Authority to which the meter readings are 6th of each month. The bills are paid from Mrs account, I can transfer money in.
Just checked the bills for 2019.
6 Jan 447.48 THB kWh 123
6 Feb 262.10 THB kWh 66 but was in Isaan most of Jan
6 Mar 780.89 THB kWh 204 more than I was expecting as spent time in MY and VN, but think Mrs was back here some of the time when I was away, bills are always higher when shes here as the aircons on more due to her doing workouts, acrobatics , yoga that type of thing every morning.
If you're renting a Condo, they should tell you what the unit charge of Electric and Water will be, years ago we rented a Condo in Pathum Wan (downtown BKK) they gave us the unit charges before we signed to rent.