If your evaluation was done improperly and you can prove it conclusively, there may be hope. If, however, you cannot show clearly how and where the improper procedures or practices were done, the court will be unlikely to do anything. Courts are reluctant to ignore or disregard the recommendations made in the custody report and rarely deviate significantly from them.
If you believe your evaluation was done improperly, this article may be of some help:
Overturning Parenting Evaluations