Return - How long do I wait?

[avenueshopswapsell]

A buyer started a return on July 11th.  I approved it the same day, asking the buyer to ship the item back and then send my a picture of the receipt for return shipping so I can reimburse.  

So far, nothing.  No receipt, no messages, no item.

How long does the buyer have?  Do I just keep waiting?

[avenueshopswapsell]

Unlikely, it was a pair of sunglasses that the buyer claimed didn't fit her face, but that it was because the frames were "open".

I think she didn't bother checking the measurements I had provided...