As a former systems consultant with Experian, I can tell you that getting disputed information off your credit report isn't easy. That's because the information originates with the reporting company (your creditor). Most creditors just dump their receivables on electronic media and submit them to the bureaus. So inaccurate information will be disseminated to all bureaus your creditor reports to. So yes, you have to dispute the problem at all three bureaus if they all have the bad information. Then you need to make sure the inaccuracy stays off.

According to the Better Business Bureau, expunged information can creep back into your file. Because creditors typically automatically update accounting information monthly, it is possible for incorrect information removed from a credit bureau file to reappear because of a pending creditor update. Therefore, you should re-check your credit report within 60 days to confirm that it is accurate and up-to-date.

Unfortunately, you will need to dispute erroneous information with the other 2 major bureaus.  You should get your consumer report from Trans Union and Equifax to verify that those errors exist, however.  Bureaus do not exchange information with one another.  Creditors submit information to the bureaus.  It generally is the responsibility of the creditor to correct errors.  But if they do not, the dispute mechanism can be used with the bureaus themselves.

The corrections are not immediate and it may take a couple of reporting cycles for your FICO scores to be affected by going that route.  You can check with the bureaus directly for their policies, but you should have documentation showing the information is in error to provide to them.

Correcting credit reports can be one of the most frustrating experiences you will have.  The ease of reporting puts the consumer in the position of needing to verify that an account or payment history is wrong rather than the creditor needing to provide proof the information is valid.