I'm still doing those surveys, which are probably not worth the cost any more given the amount of data they've got on me now lol.

Yes, I distinctly remember Play credit being able to get consumed to partially pay for orders, but I couldn't get it to cover part of a recent purchase I made no matter what I tried. I wonder if it had something to do with the fact that I was already using a $2-off->$2-app promo...