I am a handy guy and can fix mostly anything but for some jobs it's best to call a pro. They have the chems and tools and most important they have experience. IE I had some really bad carpet at a rental and was ready to pull it but my Mom suggested to at least try a pro first, even though no one in my family had ever hired a carpet cleaner before, we always just rented the machine. So I do and to all of our surprise, the carpet was basically like new when it was done! For DIY you are gonna need acid like SmokinAl said. Muriatic/pool, citric, oxalic. I would then follow up with a base cleaner to neutralize like pool shock/SH injected into a power washer with a surface cleaner attachment. As already mentioned, you are looking at a reduction at best.