Here’s a good example of when a reputable credit repair service can help you do something you may not be able to accomplish yourself. If you have a collection account that’s been sold to a few different debt collectors, it can appear on your credit report multiple times. That information is accurate but having that one debt dinging your credit score multiple times doesn't meet the “fair” standard that Padawer mentioned.
How much you spend on credit repair depends on how involved you want to be in the process. If you hire a credit repair company, expect to pay a setup fee of up to $100 and monthly service fees of up to $150 for as long as six months. If you invest the time to repair your credit on your own, the credit repair process is free. Credit repair software that costs between $30 and $400 can help you draft letters to creditors and credit bureaus.
Credit Assistance Network is one of the few credit repair providers that offers a pay-as-you-go pricing structure. You'll make an initial payment of $179 (or $279 for a couple), which gets you access to one -on-one consultations with a certified FICO professional, debt validation/goodwill letters to creditors, cease and desist letters to collection agencies, and unlimited disputes. From there, you'll be charged for every deletion CAN is able to achieve on your account - $50 for confirmed deletions per bureau, and $70 for deletions from public records. That could add up very quickly, if you have multiple issues on your credit history.
Scoring models consider how much you owe and across how many different accounts. If you have debt across a large number of accounts, it may be beneficial to pay off some of the accounts, if you can. Paying down your debt is the goal of many who've accrued debt in the past, but even after you pay the balance down to zero, consider keeping that account open. Keeping paid-off accounts open can be a plus in your overall credit mix since they're aged accounts in good (paid-off) standing. You may also consider debt consolidation.