Hi @mthomp,
Welcome to the Bunnings Workshop community, it is fantastic to have you with us.
Do you know what the walls of your shower are made of?
The first few images make me think they are a PVC panel, whereas the last image makes me think it is concrete with a few layers of paint over it.
Determining what the shower stall's walls are made of will be key to selecting a suitable paint for replacement.
As the existing paint is flaking, you are going to need to remove it before you can apply anything, as the new layer of paint needs to bond to something that is stuck fast. So, you'll have to start by removing the flaking paint using a paint scraper.
It's a bit of a tough situation because there aren't really any paints that are designed to be in showers, so you wouldn't be covered by a warranty if they were to fail. Your best option in terms of paint is likely an exterior grade enamel paint such as Dulux Aquanamel, but as it is not designed for this purpose, you wouldn't really be covered if it failed.
In saying this, as long as the surface is well cleaned and the flaking paint has been removed, it should still last for a good amount of time.
Let me know if you have any further questions.
Jacob
