Originally Posted by COpltASgldPHX

In order to get the ticket re-issued to the lower fare there has to be availability in whatever fare class the lower fare is on the flights you already have ticketed. For instance if the ticket you have is in K class and the new lower fare is in T then there has to be T availability for your flight in order for it to be re-issued at the lower fare. If T=0 on the flight you already have booked then you won't qualify for the lower fare and therefore no GARR credit.

I'm not sure I understand your example of a Y fare either. If someone purchased a Y fare it's either because they wanted the flexibility of a refundable ticket or that was the only fare class left for the flight. If the latter was so I doubt that any availability would open up for a lower fare on that flight anyway. If they booked the Y intentionally and then changed their mind and still qualified for the lowest fare they could re-issue to that lowest fare and get a refund for the difference and not just a credit for future travel.