Ok so as we know amazon warehouse have a 20% of on selected second hand or open box items.
For items that are from amazon warehouse but don't show the 20% discount you CAN still give them an attempt to get the 20% off.
What you have to do is after placing an order go to live chat and ask for the 20% to be applied manually as it didnt happen automatically at checkout. They will either come up with a bs excuse that the item is not eligible or that they will apply the 20% discount now or once dispatched, which they said to me they would do once dispatched.
Just a heads up for anyone wanting to give an attempt, worked for me and a few other members last year when they had this offer up and also can still work now as I just tryed it out.