Dark patches/ Stains on new White Tiles? Help

[Alibenson]

Hello,

My bathroom is completely new. I had not more than five showers there and I noticed dark patches/stains on some of the tiles. I tried to clean them but nothing happens. The tiles are new and I don't know what to do and how to remove them. I need some help and advice.

Thank you!

 

[Mrs Jenny]

I have the same problem , let me know if you got any solution