How do i get the rust looking spots out of my tub .

There are 2 methods here so you can pick:

http://www.howtocleanstuff.net/how-to-remove-stains-from-the-bathtub/

Good luck!

a paste of bleach and bartenders best friend powder, brush interior of tub let it sit overnight and using a standard scrub brush brush away the rust,

I would call whoever installed it.

make a mixture of baking soda and white vinegar into a paste or cream of tartar and lemon juice.

CLR or calcium lime and rust remover. Dollar tree has an off brand that works great. I've used in on my white kitchen sink.

I agree with CLR, but also with the manufacturer...It should not be reusting after 4 years, unless your mat scratched it. It may still be under warranty.