Delta Airlines Unreasonable Refund for Military Personnel Atlanta, Georgia

My son, active duty military, was unexpectedly deployed in June requiring him to cancel a RT trip ticket with Delta for dates in July.  My son is still deployed so resolving this is challenging and I offered to jump in and see what i could do.  After a frustrating morning on the telephone being directed and redirected I was told by the Customer Care machine voice that due to call volume they could not take my call - and the machine hung up.
Delta - would you like to do the right thing for one of our country's service members?
Facts:  Delta refused to provide a cash refund and insisted he take the refund in "airline credit".  Problem is he will be unable to use the credit because he is scheduled to deployed during 80% of the time available to use the credit.   So, in fact its not a refund since he can't take advantage of what they are offering.
Request - Delta provide a cash refund when an active duty military servicemember has to cancel his tickets due to military orders.