The last two requests that I recieved were for books that were NOT listed by me and were NOT on my bookshelf. How is it possible for someone to do this and what is the proper response?

I'd use the "Contact Us" link and report it to TPTB.  I've heard of this happening before.

As Alisa said, contact PBS and let them know. These glitches happen occasionally. In the meantime, decline the requests and just explain in the place provided that you don't have these books on your shelf and aren't sure how they were requested from you.

Cheryl

I know that this has happened to members in the past when they accidentally posted books into the system.  Were these books that you had searched for in the PBS system, and maybe hit the "post" button instead of the "wishlist" button or something along those lines?

I contacted TPTB about this and they said it is generlly a members oversight.  Contact them - they can tell quickly if it was on your bookshelf and why you can't find it or if it is a glitch.  They are very responsive - so that is the best course of action.   Good Luck