Income Report / COA serious problems

I’ve been trying to reconcile a few discrepancies in Income Statement and found several problems with COGS and have no clue what may be going on.

Here is a good example of a section of my COGS:

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Item Fulfillment     1/26/2007 643595 Keith Bxxxxx   $76.48   ( 76.80 is correct COGS for this item)

Customer returned item.  ( was dropshipped) 

Bill Credit 2/28/2007 32852 Supplierxxxxx Inc.      ($55.55)    ( Actual Credit was for 79.00 from supplier - drop ship)

Item Receipt          3/5/2007     1528 Keith Bxxxxx   ($23.46)   (Customer returned item, Why only $23.46 should be 76.48 )

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Another example for the same product-

Item Fulfillment 2/23/2007 644969 Catherine Lxxxxx  $23.46    $xxxxxxxxxx     ( same product as above. Why is COGS 26.46?  Sould be in the $76.48)