I have a company that doesn't charge until they have repaired the credit for your customer $0.00 upfront fees, and they provide a portal so you can monitor progress,

Ive seen them co- sign on clients loans so they can negotiate terms.
I've seen them add customers to their company credit cards.
they've removed foreclosures, tax liens etc...

i know it works because they are doing it for my hard money customers so they can obtain conventional financing.