There are literally hundreds of credit repair websites and a lot of them try to guarantee success but the reality is most of them are just a waste of money. They use methods of repairing your credit you can do yourself if you simply google credit repair templates. Their process is very lengthy and requires months and even years to get a lot of things removed and sometimes the bad marks can come back as some companies are very persistent, especially if you still owe them money.
The only guaranteed method to repair your credit is to pay off the old bills and get your derogatory balances to $0. "Well that isn't very helpful" is probably what you are saying. Since none of us just have cash laying around to do that there are other things you can do that are guaranteed to increase your FICO score practically overnight and start rebuilding your credit.
It's actually very simple. Sign up for Millennium Secured Credit Card and send them $300. Buy $90 worth of groceries on it and make the payments. Keep the balance under $90. Then sign up for www.alliedtrustdiamond.com and get a $10, 000 unsecured credit card, buy something and make the payments. Do a google search for USA Shopping Club and sign up with them for $12, 500 unsecured credit card buy something and make the payments, Eclub USA and get your $3, 500 credit card and finally Horizon Gold and get your $500 credit card.
Once all of these companies report to the credit bureaus you are going to see an immediate increase in your FICO score. Guaranteed. Then you can work on getting the bad marks paid off and removed. It's much easier to get them permanently deleted if you don't owe them any more money.