Refurbishment of "synthetic marble" stairs

Hi
Can anyone recommend someone who can refurb and polish our synthetic / engineered marble stairs? Water stained a while back and now I've managed to mark surface of few with acidic spray in effort to clean them !
Ta muchly
Colin7828

If you google it, this is what it says:-

Spray the artificial marble with a mild all-purpose cleaner and wipe it clean with a damp sponge. Rinse the sponge with water and wipe away any excess cleaner. Dry the artificial marble with a towel.

2
Mix one part white vinegar and one part water in a spray bottle. Apply the vinegar solution to any water marks or soap scum and allow it to sit for 30 to 45 minutes.

3
Rinse the artificial marble with a clean, wet sponge and dry it with a towel.

Many thanks for the info. Sadly I tried all the online "fixes" but nothing has worked very well.
Looks like stairs need "nuclear option", rubbed down and repolished by a pro. !
All the very best
Colin