If you received your credit report and found errors that you want to dispute, the addresses to each credit bureau is clearly printed on the front page of the credit report.
what about the reports you get online like the TU you get from worthknowing? I didn't see an address for them.
With that online report, I would print out your credit report from worthknowing and then highlight mistakes and write a letter disputing those items and send it to Trans Union. Their mailing address is at their website, I believe