Q: please what may be the cause of frequent overheating?

For a week now my Honda city has been experiencing overheating after I got a new driver. So he tells me he has to wait for it to cool then refill the radiator which would have been almost dry even though it was filled before starting the day. The radiator has been checked and it's not licking. It was washed because mechanic realised it was very dirty but still overheated same day. The AC is attached to the fan and I was advised to detach it although that has not been done. At the same time the battery also runs flat. What could be the cause? Mechanics seem to just be guessing. Sometimes my driver drives with 'L' or 'S', I use 'D' when i'm driving. He also leaves key in the ignition when engine is not running so the sound keeps going off until I tell him to remove the key or shut the door. He also does not turn off ac or radio before turning off engine so when I start the car everything comes on. I just need your advise on solution to this please. Thank you.
My car has an automatic transmission.