Wow, at least you got a response!
I e-mailed their European offices a few weeks ago to ask about the conditions attached to some BA/QF fares (some of these - like stopovers - used to be viewable online on the old TISS before it was "improved"). Still havenīt gotten a response.
In TISSīS defense, I seem to recall they will let you check more than one date/fare at once, and will tell you if itīs either the outbound or return thatīs sold out.
BTW, this "give us your dates" seems pretty ubiquitous in the industry. It often takes effort to find an agent who will work with you to FIND dates for a given fare

. I had to do just that with BA last week (when their US sales people wouldnīt "fish" for dates, I called their UK sales number and found an agent who would).
Anyway, sorry for the long ramble. Must be that post-final-exam cool-down effect

.
Yonatan