Just re read your post and saw you've already fitted a new main battery... hopefully your specialist can trace the apparent drain

Well this is very annoying. Garage have had the car for a few days and cannot source the battery drain.
They’ve measured the drain being 0.08 Amps.
They’ve checked over every accessible fuse, and have been unable to identify anything out of the normal. Their only thoughts being potentially a hidden tracker somewhere draining it but what power source it’s wired to is a mystery.
They also updated the instrument pack software as apparently there have been problems of them not shutting down fully. This made no difference.
So I’m no further to working it out!
Looks like I’m just plugging the ctek charger in once a week for the foreseeable!

That's a bit of a coincidence, exactly the same as mine. Chris

2014 FFRR 4.4 SDV8 Autobiography Barolo Black
2012 RRS SDV6 HSE Baltic Blue
and before I saw the light:
2011 Suzuki Grand Vitara SZ5
1998 Ford Mondeo V6 Ghia X
1990 Citroen BX GTi
1973 Triumph GT6

Please let me know if you ever manage to solve it! 🤣

Of course Chris

2014 FFRR 4.4 SDV8 Autobiography Barolo Black
2012 RRS SDV6 HSE Baltic Blue
and before I saw the light:
2011 Suzuki Grand Vitara SZ5
1998 Ford Mondeo V6 Ghia X
1990 Citroen BX GTi
1973 Triumph GT6

One thing I’ve noticed with the car locked, if I walk close to the boot/back of the car, I will have interference with a speaker in the back car or boot area with my iPhone. Surely this would indicate the speaker or part of the system is staying powered after being shutdown & locked?

Or will speakers do this without being powered on? I’m not that smart when it comes to radio waves and speakers etc!

This noise!