u/A_wicked_hangover

https://preview.redd.it/095aw8g99uyg1.jpg?width=3024&format=pjpg&auto=webp&s=74f2e2f26dabedfd845d28dcbbd1fc4a8ad41bd2

So i have this black smudge that I just cant seem to get rid of in my shower. Yes, I know its mold, but scrubbing and cleaner have had no effect on it whatsoever. Ive cleaned plenty of mold, but this is different. The drain and basin are all one piece so I cant swap it out either. Any chemical that i havent tried yet that you think would work?