Kitchen sink Tap

We have a 2018 Bourton, since we have had it, (about 2 years) we have had a constant and ongoing issue with the kitchen sink tap. It continually comes undone. It is held in with a threaded bar which screws into the tap from underneath. The tap has to move so that it can be located above the sink and moved away when the sink glass cover is closed. It is the act of moving the tap that appears to undo the thread causing the tap to loosen. There have been a couple of times when the screw has completely come out, meaning the tap is only held in place by the hot and cold pipes.
Any ideas ? 
Phil

The base part of the tap should not move when the tap is moved to the side. All movement occurs in the tap section above, which should move freely on the base. Internal scale deposit may be causing the two to move together. Have you tried some loctite on the threaded bar and cleaning the internals of the tap?,

Hi Peter,
  No, but I will now. It was a real pain in the posterior during our recent trip to France.
Cheers
Phil