Well, I am pretty sure that most FSA's allow you to submit claims beyond the end of the year... usually the claim period runs from Jan 1, through the first three months of the NEXT year... so say Jan 1, 2013 all the way until March 31, 2014.
So you have longer to spend the money...
Does no one in your family take regular prescription medication? Or wear eye glasses or contact lenses? Surely you get your kids eye exams on some sort of regular schedule, right? And it is only May... a lot could happen between now and next spring. I mean.... you could break a tooth and need an implant. There's $3,000 right there. And you don't always know about these things in advance...
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ETA:
Oh.. and I am a stickler for documenting. Personally, if it were me, I would take it higher up the chain and get a supervisor to tell me they couldn't care less about the charge adjustment... and then I would insist they send that to me in writing. While waiting for that to arrive, I would write a letter detailing the conversation and documenting the adjustment to charges and send that to them as well, and keep a copy for my own records.