Vinyl showers............

It may not have been properly cared for by the previous owner. Our new "plastic" shower said to use Tob Job. But if the surface has already been damaged I would seriously consider having it resurfaced.

Try some Softscrub with bleach, maybe leave it on for a few minutes. Use a lot of ventilation, it will burn you

Catch it while warm and use Ajax. Double check and make sure the surface can stand the scrub.

If it's the kind of plastic I think it is, it yellows with age and there isn't a thing you can do about it. I have a 25 yr old freezer with a plastic handle that's done the same. Check prices on shower surrounds, they may be cheaper than you think.

Put in washer on gentle, then hang to dry and smooth out wrinkles.

Not sure if it will leave it white, but I use a HOT vinegar mixed with a squirt of dish soap [Dawn] on my shower walls. Spray on, leave it for awhile, rinse off.

try bleach

I have heard, but never tried it.....rubbing compound that they use on cars will do it.

While I know my answer is not going to be a popular one and you will doing this at your own risk, and I will not be held for damages to property or person. We have had horrible problems with hard water and rust stains, to the point of having to replace the entire shower insert and glass doors. I figured I had nothing to loose. I used the hottest water available via tap to spray the shower to "heat" up the surface. Then using an inexpensive oven cleaner, sprayed the entire area, being very careful to ventilate and not overspray onto ANYother surfaces. I let it set for at least 6 hours and them wiped off the cleaner, I rinsed that same area several times to remove ANY residue. It worked beyond belief

Thank-you one and all for your great ideas!

Hope it works. My grandmother used Ajax powder on tons of stuff! I love it too.