ADE "Already fulfilled by another user"

Hi,

I've been buying ebooks and loading them into ADE to then put them onto my eReader, this has always worked fine without problems until now.

I puchased another eBook but when I tried to load it into ADE it didn't work because I had some problem with authorization. I googled it and tried around until I got to deauthorize over the regedit window. When I tried to reauthorize I  at first had trouble remembering which email / password I used so I just chose to do it without an ID. I could then load the eBook into ADE though there still were some problems with getting it onto my eReader. When I later authorized over my ID again because I thought that might help I always got the message that the eBook acsm was "already fulfilled by another user". I already contacted the seller who provided me with a refund so I could buy the eBook again, which was recommended by Adobe on some support site. But I still have the same problem with the new acsm file and I frankly don't know what to do anymore. I can't even contact the adobe support because this chatbubble thingy doesn't show up even though I tried in different browsers. Is there some way for adobe to connect that eBook with my ID again ?