I had requested a book that got timed out on twice, before the next sender sent me the copy.  Neither of the first 2 senders sent the book before it timed out in the system, or they did, but they never marked it mailed.  So, of course, I ended up with 3 copies.

One of the senders asked for a credit back, and I politely quoted the help center saying, If you received (or will receive) two copies of the book, you are not obligated to give a credit to the sender whose transaction was canceled. 

So now that sender is asking for me to mail back the book so it can be reposted to her bookshelf.  So I'm out postage, too.  I'm trying to be polite about this, but what you do guys suggest?

I believe that the help center also says that you do not have to mail the book back and if you do you should get reimbursed for postage.  Often people send an additional credit to cover postage.  I don't know that the original sender would be willing to do that.  Personally, I would just leave things as they are and chalk it up to a learning experience. 

You do not have to send the book back unless they give you postage in the form of a credit or money for postage.

Susan is correct, you do not have to send the book back unless you post it and she wants to request it and thereby giving you a credit or buddies you a credit to cover postage

it isn't your fault that they didn't following the rules and mark the book mailed.  If something came up they could have sent you a PM to say the book was mailed they just forgot to mark it as such.  This way you would have ordered the other copies

I am sorry your in this spot. I have to agree, the rules are clear, you do not have to give a credit and you do not have to mail back the book unless they some how cover the cost of shipping.   

Yep, I wouldn't give the credit back either! The way people learn not to make those kind of mistakes (and it WAS their mistake for not marking the book mailed!!) is to get 'burned' for them a time or two. I bet they are much more diligent now about marking books mailed. If they give you any more guff about it and start demanding things, point them to the help docs that are relevant and if need be, report them to PBS if they continue to hassle you.

Cheryl

I agree with everyone else, you don't have to give them a credit for the book and if they want their book back, I'd get a credit up front from them or postage money up front before I sent it out.

How strange to have this happen twice on the same request though!  Must be a cursed book.

It's funny, because I had a similar problem, well, not so similar, but....here's what I mean.  I requested a book and the "Sender" waited over a week, after the MAIL BY date, and then canceled the book.  That's infuriating, I don't have that credit to use and then I lose any chance of still obtaining the book. 

Point is, if you don't play by the rules, it's your own fault.  The recipient shouldn't have to bear the burden of someone else's irresponsibility.  (Wow that soundy touchy.  LOL)

Thanks for all the advice.  I just always feel like I'm not being nice enough, by not giving back a credit or sending the book.  But I have to agree with the rules, too.