Advanced Genioplasty and jaw contouring disaster. What are my options to fix this problem?

Genioplasty is a very powerful procedure to enhance the lower third of your face. The dent that you are seeing is the consequence of the gap created by the osteotomy. That gap can be filled either with temporary fillers while bone grows and fills the site, or a custom made iimplant can be placed to make the contour of the chin accord to the mandibular bone segment.
In your case a revision genioplasty could also be performed very carefully trough 3D surgical planning.
Best regards,

Easiest plan is a combination of Sculptra and Voluma HA fillers abut 30-40 cc's of the mixture. Fee $3,000. Otherwise might try fat grafting (fee $5,000). I wouls try to avoid surgery.