We were scheduled for an SVI charter from 25 Oct to 04 Nov, 2017, flying into STT on Delta with non-refundable tickets. It took about an hour, but today Delta re-issued those tickets with no change fee and no fare differential for Apr 18 to Apr 28, 2018.
The hangup is that we had purchased our tickets direct from Delta (no travel agent) in early Feb 2017, and the official hurricane policy for such tickets is that (1) only re-booking fees will be waived (any fare increase must be paid) and (2) travel must be completed within one year of the ticket issue date. I was able to convince Delta to waive both restrictions for two reasons. First, it is fundamentally unfair to punish with a short travel deadling those customers whose money Delta has held the longest. Second, the hurricane policy applicable to tickets issued by professional travel agents contains neither restriction. Here is a Dropbox link to that policy. Delta Professional Advisory: 2017-09-21
Act quickly, because both the lay and professional policies have a re-ticketing deadline of Oct 31, 2017.