Improving on credit post-bankruptcy and improving on your credit report are two separate things. Dealing with information on your credit report is often founded in whether the information is accurate. Accurate information, even if negative, cannot be fixed on your credit report. Bankruptcies, for example, stay on your credit report for 10 years while other negative but accurate information can stay on the credit report for up to seven years.
If you do have inaccurate information on your credit report, however, there are steps you can take to resolve the issue. This happens sometimes after a bankruptcy if a creditor neglects to update the information that is reported to the credit reporting bureau and it can have a negative impact on your credit. In that situation, you simply mail a credit dispute letter detailing the issues you have with the particular debt and provide proof it was included in a bankruptcy. You send this to the three credit reporting bureaus and they are required to respond to you.
Once you have done this, the issue should be resolved. Because this is an issue that sometimes happens after filing bankruptcy, it is something that you should definitely discuss with your experienced bankruptcy attorney.