My daughter dropped a heavy bottle of shampoo on the tub spout while in the shower, causing it to become loose. Water now leaks behind the tub and comes down through the ceiling downstairs! I have a new spout kit but the problem is that the pvc pipe coming out of the wall through the tub is too short and not centered in the hole. I have a brass slip-fit adaptor but I cannot get it to go on straight and there's not enough room to use the allen wrench in to tighten the screw. If I could enlarge the hole in the tub just enough to allow me to get the adaptor on straight and enough room to use the allen wrench, I think I could fix this problem. What kind of saw or tool is needed to do this? It's a fiberglass one-piece tub/shower.

What is the next room over behind this tub? Can you make an access opening from the next room. Many homes this space is a closet or even another bath if you are lucky.

I am not lucky. The other side is a wall on a hallway. I was praying I wouldn't have to go through the drywall. So, if I need to go through the drywall, what are the next steps?

Was the pipe coming out of the wall damaged? You have PVC pipe coming out of the wall and not copper? If you had a slip on spout before why can't it be replaced. Can you be more specific with more details? Back to you, Tom

Can we assume that the pipe coming out of the wall is 1/2" CPVC?

Here are pictures that I hope will explain it better.

The middle picture is the old spout just as it was when I removed it.