Bill of entry differs with po

During import process . after creation of PO when client goes to do MIRO he founds in bill of entry that freight is changed consequently Accessible value changes (including custom duty also). then he corrects duties for each line items .he is feeling difficulty to correct duties for each line item because he gets around 200 line items .he wants solutions for this in standard. is it possible to do something in standard.if not what is right solution.