If the siding extends to the ground there must be some wood framing behind it which sets up a perfect entry for termites and other pests. Two things come to mind that can be done (neither of them easy).
1. Dig the earth away from the house to expose the foundation. I would make the dig 3' wide at the bottom and on a 45* angle away from the house. The bottom of the dig also should be sloped away from the house and a swale or French drain should be installed to keep the water away from the house.
2. Remove enough of the wood framing and siding to get it to the required height and replace it with concrete blocks or solid concrete, stepping it down to where there is no problem. Water proof the wall and replace the dirt with a slope away from the house.
These are just ideas and more detail can be added if you need it. Let us know how it turns out for you.