We are staying in a rented home with a spa bath. Attached to the spa bath is a hand held shower. The showerhead rests above the bath but the pipe coils somewhere between the tiles and the bath and can be pulled out when in use. The shower head has come away from the pipe and the pipe has dropped down into the gap. There is only a small hole in the actual bath where the shower was attached so I can not get in that way to reattach it. There is row of small black square tiles between the floor and the larger white tiles down the side of the bath. One of these black tiles looks like the grouting has been removed before. Would that be the way in? What is that tile grouted to? only the tiles surrounding it or would it be attached to something behind too?

The grout between tiles is just for filling the gaps. The tiles are glued to the wall, usually with "thin-set" mortar. Unless that mortar is in very poor condition it is unlikely that you would be able to remove that single tile without breaking it. The wall behind the tile might be water-resistant drywall (a poor quality situation) or it should be cement-board. I suppose it's possible that there is already a hole in the wall behind the tile, but the hole would be smaller than the tile, and assuming 4 inch (not large) tiles, this is a poor choice to gain access to the pipes. The usual access is through the wall from the other side. During initial construction, a removable access panel is sometimes provided (depending on local building codes and whims of the builder). If there is no access panel, and the other side of the wall is drywall, then cutting a generous hole, and fashioning a plywood panel (with trim around the edge to cover the gap between the drywall and the plywood) is a pretty standard and simple approach (depending on your skills). As an alternative and for more info, here's a link describing how to install a plastic snap-in access panel. Good luck! http://www.diylife.com/2008/06/23/plumbing-access-panel-installation/