Correct Receipt Issue using WEB Service

When We Create A Receipt Correction through web service (SOAP UI) Because the Line Type in PO is a fixed price service the adjusted amount (returned amount) is Reduced from the delivered amount in the PO Details but not from the received amount.

Let's Say We Have PO : Order Amount is 1000 LE

Received Amount is 500 LE

Delivered Amount is 500 LE

When I correct Receipt for - 200

The Received Amount will be 500 LE

Delivered Amount will be 300 LE

I want to Reduce the both amounts