Follow up: We used them in our full house renovation and we have a problem in every bathroom where they are located. We don’t have any problems in the primary bathroom, powder room or kitchen where we used other brands. This leads me to believe it is the fixtures and not the subcontractor.

Your plumbing may be different, but this should give you an idea. The shower head is threaded on to the shower arm. The shower arm simply threads into a fitting in the wall. You can unthread the shower arm from the fitting and thread a shower head and arm of your choosing back into the fitting inside the wall. Use teflon tape to make up the connection. The tub spout may be the same. In the drawing below, the "nipple" is what is shown between the tub spout and the fitting in the wall. Nipples are simply short pieces of pipe threaded on both ends. Some tub spouts are threaded on to the nipple. Some slide on and are held secure with a set screw that may be visible from underneath. Again, use teflon tape to make up any connections. The valve is the wild card. The valve body (the big hunk of brass in the wall) typically needs to be set a certain distance back from the face of the shower surface (typically tile, or in your case the plastic surround) to ensure that the valve cover plate will sit flat on the wall. There's a bit of leeway here. You will likely be replacing that tub surround with tile backer board (say 1/2" thick) plus thinset and tile (say 3/16th" thick). You might not need to make adjustments...or you might have to. If required, to move the existing valve in or out a bit, often time fasteners that secure the vertical runs of copper tubing to the wall studs can be removed. The valve (and the associated plumbing) can be pushed back a little, or pulled forward a little, and the fasteners can be reset to hold the valve in its new position. It's always a very smart idea to replace the shower valve when redoing a shower. A nice basic shower valve like Symmons Temptrol is inexpensive with replacement parts being easy to find.

There are some styles that wouldn't look right, even across the room from each other. However, I have a Kohler shower set, Moen sink faucets and towel bars and a Jacuzzi tub filler that came with the freestanding tub. They are close enough to each other that probably no one else is going to notice they're not from the same group. Check the return policy on anything you buy and see if they look good together in person. I found things look a little different IRL. Chrome and brushed nickel are finishes that don't vary much or at all among manufacturers so you're going to have better luck blending if you use those finishes.

The way the internals of plumbing work is not rocket science, and long lasting finishes and excellent quality internal parts are features of even moderate cost fixtures. So don't confuse spending a lot of money with "best." There are many moderately priced fixtures that will perform just as well as pricy ones...and a US-based company may have replacement parts more readily available when you need them in 10-20 years than some exotic item from, say, a small city in Italy. Look for name brand manufacturers that have been doing business in the U.S. for a long time and who offer lifetime warranties. Look at the styles you like without regard to price. Look at reviews after you narrow your choices down. And if the fixtures you like don't cost an arm and a leg, don't feel you made a wrong choice.