Fix shower to bathroom tiled wall that's become lo

The shower in my bathroom has just become loose from the tiles. For example if I take the hose out of the holder to use the shower directy on me - the pole comes out from the wall. It's not secure. It's fine as long as no one tries to take it out from it's holder but otherwise it needs tightened back in another screw/plug or whatever. the screw is all rusted. That's one shower. And I have a similar problem with another shower above my bath - but it's not as bad. I thought if someone came they might as well fix both. The shower pieces themselves are fine as far as I can see.