Not properly mounted / "light professional" unreasonable

If one so mounted the holder wall, as required,
Namely so that no water can run into the interior, is the
Lamp not mounted because the detector electronics is there,
where the wall bracket, the recess for the cable bushing
bulges inwards.
The seller "light professional" is on top of that I do not recommend.
Complaints must be sent back at his own expense, the
Porto will not be refunded.