There were two different deadlines. The September 30th deadline would have applied to the specific details of the legislation itself, which probably mandated the funding be spent within FY 2019. Had the suspension gone beyond that, the appropriation would have died and a new FY 2020 appropriation would have been necessary. That would also have mandated a White House explanation on the cause of the suspension. However, the second deadline would have been the Impoundment Control Act, which mandates that the President first inform Congress of his intent to suspend aid and the cause of such suspension. That was never done. AFTER such notice (which was never done) then Congress has 45 days to respond. If they fail to approve or to disapprove, the aid must go forward.