Amazon Easy ship fees

Hi guys!

I Just Started My AMZ Journey and i just received an order on amz in FBM Easy Ship My list price was 30.00 DHS And Shipping was 10.00 DHS+COD 10.00 DHS Total It Was 50.00 DHS To Be Charged From Buyer, Amazon Easy Ship Fees Was 16.28 DHS and Referral Fee was 6.50 DHS as Shown By AMZ Revenue Calculator, So it was 22.78 DHS in Total To be Deducted By AMZ, But Amz Charged 15.47 Referral Fee Instead of 6.50 DHS

CAN SOMEONE HELP ME TO SORT THIS ISSUE I MIGHT BE MISSING SOMETHING

MANY THANKS IN ADVANCE