Adobe Digital Editions DRM Authorization issues

Hey There, 

I brought a $40 Ebook from a bookstore about couple of days back. On the website I downloaded an ACSM file and opened it in the Adobe Digital Editions application. Once I opened it, I was asked to authorise the book. Unsure of what the Vendor ID is and how I should find my way about that, I authorised the book without a Vendor ID and was able to view it on my PC. But a few days later I accidentally erased this authorisation, upon doing that I thought it's okay, Ill just authorise it again but no. When I tried to reopen the book it asked me for the Vendor ID and Password. So at first I thought, okay maybe now it wants me to authorise the book through a vendor ID but when I plug in an email address and a password it says , "The Vendor Account you entered is not associated with the item you are trying to open". In the first place I didn't authorise it with a Vendor ID how and why is it asking me for a Vendor ID now? I cant access the book anymore and I am stuck, Please Help me out. I was on a chat with Adobe for 40 minutes and all they could do is tell me to make a post on the forum, I am very agitated with this management of the situation could someone or the staff please help me out.