This is from the Delta.com website.
If I have purchased a ticket and a new fare is introduced, can I obtain a credit?
Yes, in many cases you may obtain a credit voucher (non-refundable tickets) or refund (refundable tickets) at any Delta airport ticket counter, City Ticket Office location, or over the phone (e>tickets only) for the difference in fare. A fee will apply for non-refundable tickets purchased for international travel.
When we introduce new fares or reduce a current fare in a particular market, you may change a ticket to the new fare if:
the change is made prior to departure
you do not change the flight, date, origin, destination or stopover points
reservations are confirmed in the appropriate class of service
all fare restrictions are met
the lower fare is not a special delta.com only fare
Any applicable penalties are retroactive to the new fare ticket.
It really is not who you know, it is where you purchased the ticket and the type of fare.