I found another way to save credits on Bing which is part of "My Amazon Credit Guide"
This isnt much but it will save you 5 credits when purchasing a $5 Amazon gift card.
Instead of purchasing the $5 Amazon cadr instead opt for the $5 Tango card. The Tango car is 5 points cheaper. You can then go to the Tango website and use the $5 card to purchase a $5 Amazon card among other gift cards not offered my Bing.
For full details on how to get free Amazon gift cards, read my post
My Amazon Credit Guide - How I Get $180-$240 per Month Free!