John,
On the later cars it is a metal box about A5 in size usually just laid flat in the fuse & relay box, it's called the 'body control unit' and is full of electrickery best left alone, within this is a 'interior light control' which will be the delay timer which I suspect has failed
One thing worth checking is ALL the fuses as the BCU has lots of internal connections dealing with light circuits & as LED's will run off such a tiny ampage a blown fuse to a seamingly unrelated light may still be enough to backfeed a supply
I think your fusebox top should be labelled, but this should help too...
FUSE IDENT BODY
1 = HAZARDS 10A
2 = SIDE LIGHT SWITCH 10A
3 = POWER SKT / MAP LIGHT 15A
4 = RADIO / COURTESY LIGHT / CLOCK 10A
5 = BODY CONTROL UNIT 2A
6 = RADIO / HORN ACC 10A
7 = BODY CONTROL UNIT 5A
8 = BODY CONTROL UNIT / FROSTAT 7.5A
9 = REAR / FRONT FOG 15A
10 = HEATED SCREEN 15A
11 = HEATER 10A
12 = WIPERS 10A
13 = INDICATORS / HEADLIGHTS 15A
14 = REVERSE / BRAKE LIGHTS 15A
15 = MAIN BEAM O/S 10A
16 = MAIN BEAM N/S 10A
17 = DIPPED BEAM O/S 7.5A
18 = DIPPED BEAM N/S 7.5A
19 = O/S SIDE LIGHTS & DASH ILLUM 7.5A
20 = N/S SIDE LIGHTS & NO. PLATE 7.5A
One final point is that a 2016 car should still be under warranty ?
