There are specific building codes regarding the distance of the grading from the header beam. My last home was 8" but that was up north. Perhaps 6 in TV's. See link below as an example, but prudent to check the codes, my builder was professional enough to regrade to meet the specs. However if the grading was within codes, the landscaper may have dumped X? inches on top of the grading,
Please be so kind as to update this post when determination of culpability has been established as it could impact many other homeowners, thank you
Keep us posted
Link
Siding to soil clearance | Spot On Inspection