White marks on shower tray! Wont go away!!

[TomV87]

Good evening,

Just wondering if anyone can help me with some white marks on my shower tray.

I have tried all sorts of cleaning products and they will not go!! There is one part near the shower door which is about the size of a palm. Nothing I seem to use works :(

The shower tray is two years old BUT has never been used properly as the bathroom has only just been finished, so it is effectively new.

I have enclosed two images of some of the spot marks which have appeared.

Can anyone help?

imgur.com/a/CLZNj

imgur.com/a/OkVUX