Does your 2015 Chateau have the Thor 3TRAX system that was installed starting in late 2014 or was yours manufactured before the 3TRAX system was put into production?
If my memory serves me correctly the price quoted is consistent with what others paid when retrofitting their early 2015 and older full wall slide rigs rigs a number of years ago.
As a note, the issue with the slide wasn't limited to the Chateau. The issue with the full wall slide track system extended to all models having a full wall slide.
Here is a link to the 3TRAX discussion started on the forum a few years ago.
https://www.thorforums.com/forums/f1...em-1722-4.html
If your rig has the 3TRAX system then the issue may be incorrect installation or alignment during the build or prior service.