Disconnected the battery and left on trickle charge for most of today and it works :)
Have connected the solar trickle charge via the cigar lighter socket so lets see how it goes...

FYI - The solar charger through the front cigar lighter works :)
So, no more drained battery when I leave the car for long periods.

Cheers

Thats a stroke of luck.

Got any specs for it?

Result.. Is the keyless all working properly again too?

Nope :(
Will get in touch with Audi and book it in to see if I need the update that Nick had on his.

If you've got power again, do a VCDS scan and see what errors you have (if any). And check the carpets (probably underneath them too).

No VCDS.
In the MMI, the battery shows as less then 10%, but with a multimeter it has 12 volts.......

Think this is what Nick had - when everything works the MMI shows battery as good, but when things don't work, MMI shows battery as bad even though battery shows plenty of charge.
Will check the carpets though +++

let me know if you want it scanned

If you update MMI beyond a certain point it turns the battery meter off as it basically doesn't work properly :) You can turn it back on, as I did, but no matter how well the car started or how long it had been run it showed either <10% or full.

Mine has showed 75% a few times :D