The CRA's (credit reporting agency) are going to do what they are going to do regardless. You have the right to dispute anything they report of course but to do that you need real-time info on all your accounts and your score and rating. Are you subscribed to a score watch? IMO there is only one valid rating company, FICO.
http://www.myfico.com/ There are many others but they ALL offer what is known as fako scores. Only Fair Issac guarantees accurate scores from Trans Union, Experian, and Equifax. Check their site, they usually have a free 30 day trial.
You need to find out which account uses which CRA. Some credit cards always use the same one, some use two, some switch around. Getting a hold of your credit report is a good starting point. On it you will see which CRA's your accounts are using. There is of course a lot more to it but maybe this will help get you started.
ps To affect credit score ratings you will have a time lag, usually clearing up problems might take one, possibly two statement cycles. Of course bad news travels fast, adverse action will be picked up much faster.
hth