There are a lot of reasons that your credit may be in rough shape. Most are related to your spending habits. And, if you missed a few payments or your debt levels are too high—think over 30% of your total available credit limits—disputing errors won’t help you. You’ll have to make some changes to improve your credit scores instead. And you may have to wait a bit to see an uptick.
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.
Credit scoring models usually take into account how much you owe compared to how much credit you have available, called your credit utilization rate or your balance-to-limit ratio. Basically it's the sum of all of your revolving debt (such as your credit card balances) divided by the total credit that is available to you (or the total of all your credit limits).