I sent mailed out a book Wednesday with DC to a member in Ohio.  I recycled another mailer that had my addy on it, so I used a marker and marked the other mailing info.  I covered this with another piece of paper and wrote the new addy on it.  This was well-taped on the mailed--all around the edged and a "T" across it as well.  Today I get it back, b/c somehow the sheet was completely torn off, so of course under it was the old mailing label addressed to me.  My DC sticker had been totally blackened out with a marker.  What pisses me off is that I had stamps on it to cover the entire cost, and it was mailed from a P.O., so I know it was on there when it left.   I don't feel I should have to pay the postage costs again, since apparently it was the carelessness of the processing center that caused the address to be ripped off.  I'm going to the main P.O. Monday and see if I can get the postage costs reimbursed.  Has anyone had any success with this?

They'll probably just say you didn't tape the new label down well enough (although it sounds like you were thorough!). What did you tape it with?

First thing that popped into my head was what kind of tape did she use.....if it was packing tape, it should of held, but if it was scotch tape....probably not?

Dawn is a seasoned mailer and game swapper, I'd be surprised if it wasn't adequately packaged. 

Print another label Dawn, and take it to the PO with you and ask for an explanation.  You can re-apply the label at the counter and ask about postage reimbursement (do you use pre-printed?  I buy at the counter).  And let us know, I've wondered how USPS handles legitmate claims for postage reimbursement such as yours :-)

ETA:  I use very clear packing tape to cover the entire shipping label, the counter clerks add postage sticker on top of my tape.

I always use packing tape and if I don't "t" an attached label, I will at least make a vertical or horizontal full-package tape across it.    It irritates me to be out another $3.57 (book + DC cost) because of something THEY did wrong.