I had a diverter spout which, over time, collected enough limescale that when using the shower, 1/2 the water came out of the spout and only 1/2 came out of the shower head. Impossible to clean, even with CLR.
Advanced noticed the pipe stub was composed of a smooth copper pipe, then a connector, then threaded pipe out of that, so they had to switch the diverter spout choice to "screw it to the threads on the end" from "use a set screw at the other end".
And it did not help when you looked from under the spout, it looked like the smooth, set screw type, only, no there was no set screw. Of course, Murphy's Law applies with house repair parts, always.
Now I don't waste water and have actual water pressure at the shower head. I have been putting up with this for far too long, frankly. I called them and they came the next day. Well done job, 24 hour service.
Note I had them come by before and they showed my why the toilet bowl bloops on flushing which is a feature not a defect and reassured me something was not wrong.
This kind of fast, helpful and thorough service is why I patronize independent service businesses in my neighbourhood.
Once that was obtained, smooth as silk.