Well, just come back to post again.
Last 4 hours using my GS3 plug and the Note 10.1 cable to charge.
Now the battery has dropped to 12%!!!
Managed to boot the thing up - it was turned off - battery usage monitor says the screen has been using 62% of the battery. How come, it was switched off. Nothing should have been sucking the battery.
Can only think that the USB cable is shorting somewhere maybe and causing the battery to discharge.
Beginning to regret buying this thing.