Help with dingy area

[jsjanitorial]

I'm in the middle of cleaning an office attached to a grimy warehouse. The carpets were last cleaned with a rug doctor. I don't think anyone ever vacuums if so rarely. They track in a lot of greasy type soil from the warehouse. I'm getting decent results with ds2 and punch..but some areas have very dingy gray areas. The carpet is matted. I have made multiple passes with max pads..but still dingy. When I spritz with spot and use a white cloth i get tons of soil transfer

I think a crb with powder would be great but don't own one. Should i extract with porty or hit with 175 and microbeast? How can i better prepare I the future as well?