I returned five bottle to Whole Foods yesterday, and received $124 in store credit.
Since I had read about the differing experiences with returning bottles that others of you have had at different WF stores, I decided to just see what happened. At first, the customer service guy tried to tell me that I needed to do an even exchange for a new bottle and I told him about my concerns about Sigg's integrity as a company, and that I had no interest in using their products ever again, as I do not trust them. I said that I had called WF's corporate office and they had told me that I could get store credit (small fib, I know, but I really don't feel guilty about it, given the fact that there seems to be no consistent policy), and he called a manager over. She said, "No problem."
So, with a little perseverance and creativity, it is possible to still get a store credit at WF.
Of course, $124 doesn't go far at Whole Paycheck, but that's another story...