Small cavern under pool deck

I am a disappointed new home owner.

Not myself nor the inspectors caught the cavern underneath the piece of decking that butts up against the skimmer. Looks like their dogs dug under at a point. The seam or grout?? line has separated about 3-4mm on one side of the pie shaped segment and it appears to be raised maybe 2-3mm. I will provide pics when I get home. Sidebar on this is the cavern is a couple of feet away from the back fence/property line and this area of the fence has a crevice that looks like pool water actually ran for a while down at some point in time (maybe a few times) so this is a 3-4 foot embankment essentially that the edge of the pool deck is near. I have heard of mud-jacking and stabilization and taking off the deck segment and am so nervous about the potential of a breach and then the cost of course. This house turned out to be a fixer upper and this was never the intent.

How can I get this little piece reinforced underneath so that I can further embark on the terracing at the fence line...or are they part of the same problem?

If there is a thread addressing this point me there and I'll gladly read :-)

Thx.

I doubt there are any threads that are directly relevant; repairs like yours tend to be somewhat unique.

Posting pictures would be a GOOD idea. You can use Picasa, Flickr, Webshots or Photobucket.