Is Sagoni Melt safe and does it work?

Thanks for your question.  A quick Google search tells me that the Sigoni Melt is a topical treatment made up of an acid and other products.  I don't see how applying an acid on the surface is going to melt fat under the chin.  It seems like a set up for bad chemical burn...
The FDA recently approved the SculpSure laser for treating submental fat (double chins).  It is a quick 25 minute treatment.  In the FDA study, the participants had 100% satisfaction after 1 or 2 treatments.  If you look at the Kybella FDA studies, there is high satisfaction after an average of 6 treatments.  I did SculpSure recently and it was only mildly uncomfortable.  I had no noticeable swelling.  With Kybella, you will have noticeable swelling for 1-4 weeks.  Best of luck.