Share my experience.
Before normal aircon. On at nite only, ~10hrs per day. TNB bill is rmXXX.
After change to inverter aircon + 3-phase supply. Aircon on ~20hrs per day. TNB bill still rmXXX.
I believe the 3-phase also helps. Using Panasonic inverter aircon, temp at 22-23degC. Terrace hse.
R u sure ur aircon is inverter? checked n confirmed urself?
After we replaced our 8yr old fridge w new one (non-inverter), TNB bill also drop by ~15%.
Plan to buy inverter only for all future appliances like fridge, washing machine, aircon, etc...