I feel for you. This sounds almost like a problem without a solution. I'm not really competent in these matters, but want anyway to toss out some ideas. Have you considered trying to wedge a large iron slab under the granite and gradually hammering it under? You might then be able to lift it? If you cannot do it yourself, can you find a contractor whose promises you can have confidence in? One possible compromise, if you haven't thought of it: Unless you're really attached to the look and feel of the granite, which I can understand, you might consider applying something over it, which could be tile, brick, or whatever.

Good luck.