Sorry to hear you have been having issues reaching Southwest in regards to requesting an exception for an extension on your voucher. From what I have heard they will on a case by case situation re issue travel funds as a LUV voucher (not sure if they do the same for a LUV voucher) if they do they will probably deduct $100 as that’s what is done when travel funds are issued as a voucher.
To request an exception I would reach out to customer relations at 855-234-4654. Note that if they are able to re issue you another voucher it can take up to 14 days to get the voucher (this time frame is what I have heard from others). You could also try to reach out to Southwest on Twitter and hopefully they can assist.
The Customer Service group is likely tied up with rescheduling due to Tropical Storm Barry. The storm is squarely across their flight routes.
Sorry that you have to wait; however, I have not seen much success in getting any airline to honor expired vouchers, so the answer may be as frustrating as the wait. I am just letting you know my experience so that if you have other demands on your time, you may not want to wait. I hope your travel emergency gets resolved quickly.