Now im not talking a few months grime/shit, im talking about something that looks like its never been cleaned, its completely black, not even a tiny speck of silver can be seen

Ive tried what i normally do on my cars, a old cloth and AG metal polish but its not touching it, so would i need to use wet+dry paper on it? would that work?

I wouldnt let mine get this bad but i bought the car like it(rest of the car is very clean)