Some things in your Node setup don't appear to be doing much (eg the bottom half Voronoi looks like it's cancelled out by the white ColorRamp and then just adds white to the top part?). But - never mind that, the problem is that you're using Generated Coordinates. As a result, the Mapping nodes are probably not doing what you expect.
Generated Coordinates treat one corner of the object's bounding box as (0,0,0) and the diagonally opposite corner as (1,1,1). You can see the effect of this if you momentarily set the Mapping Node to 'Normal' - you should see the Voronoi spanning out from one corner in a radial burst pattern.
To fix it how you want, you just need to UV unwrap the object, and use UV coordinates for the shader input instead. There are other fancier methods, such as blended box mapping, but the quickest/easiest way to get to the result you want is to go into edit mode on your object, select all faces, then hit U > Smart UV Project.
This should do a decent job keeping all faces scaled and aligned properly. After doing this, change that Texture Coordinate node to feed 'UV' output into the Mapping node instead.
This will mess up the scaling values you have already set, but setting those back to 1,1,1 should give you a correct baseline from which to set proper texture stretching and expand the Y direction as desired.
If the Smart Project doesn't perfectly fix all the mapping areas, you may need to do some further reading on UV mapping/editing and fix some areas manually.