Hi guys after a bit of help, my HTPC (specs below) was running 7.0.3 and CEC was working fine, switched off when TV was and woke up when TV was turned back on,
not sure if it's the same, but our master bedroom TV tends to wake us up each night around 3 o'clock with a 66% chance.
But I am using not a PC but a Raspberry Pi3
Same in the living room with an Raspberry Pi2 and a 20 % chance.
Both are Samsung TVs with Anynet/CEC
Both TVs didn't show this behaviour before Kodi 17