Keep complaining. This has happened to me since Christmas as well and I've now had to download every book I purchase no matter how I purchase them to be sure I can keep them. (Stripping drm to be sure). They refunded me the 30 I spent on the first three this happened to.. twice since the first time didn't stay. (Figured they would fix the glitch of the returning 10 credit before the 30 could be just as glitched -might be why they removed it before I had 30 to spend over and over...)
Beyond that point, I'm having the same trouble or was... the last two stayed in my account this time. But I still didn't get the receipts, nor are they in my purchase history.