[rhyds]

Do you have a smartphone with video functionality? If so, set it to record and put it in hte boot and glovebox to make sure the lights in both those places go off when you close them.

If its still playing up then you'll need a decent multimeter and someone who knows how to use it to measure the car's current drain with everything switched off. Culprits can include radios not turning off properly, faulty alarm systems or in some cases the alternator itself failing and causing a drain when the engine is stopped.