^ I found out that hard way. Apparently as soon as a locator is generated using a discount code is is considered "used" in the amazing ResIII system, irregardless of whether an e-ticket is issued.

If you have booking on hold and make a modification within the alloted timeframe before the ticketing deadline, then adjustments will reflect the discount (unless non-AC segments are added then it can reject it as invalid).

Very true about cancelling Lat bookings - I always call in. Some agents say everything works perfectly online, however, it doesn't. I only consider it refunded when the credit note pdf arrives in my inbox.