There's two ways you can go about getting the credits due to you red,
1, Send an e-mail to members@worldgolftour.com
2. Go to the credit offer page here, and look for the "Contact Support" button at the right of the page. Look for the offer you completed and click "Contact Support" again. Give them your confirmation e-mail information you received after completing the offer.
WGT and Trialpay will work with you to obtain your credits.