A good credit repair company first pulls your credit reports from each of the three major credit bureaus in order to pinpoint your credit issues. Why all three? Because each credit reporting agency has its own “data furnishers” (aka lenders, credit card companies, debt collectors, etc.), that report your credit information to them. And there may be errors that appear on one of your credit reports, but don’t appear on the others
If you find information that is incorrect, you can file a dispute. Remember too, that items on your credit report that you don't recognize could also be potential signs of fraudulent activity — someone working to secure credit in your name for their own use. Make sure you're clear on items that could potentially be fraudulent, versus those that may simply be inaccurate.