Uneven jaws after double jaw surgery. Is there anything I can do to fix this or help with the appearance? (photos)

I believe the the best thing to do is redo the jaw surgery unfortunately.  You may also want to consider fillers if you just want to  correct the indentation

The areas of 'dips' relates to the osteotomy/bone cut areas. Your growth pattern can result in this appearance after surgery is the esthetic features of the pattern are not considered. You can augment the jawline and improve the specific contour areas of concern without extensive surgery. Fillers do help as you have tried, in a temporary way; but do not address all the areas from the chin to the angle of the jaw (which creates facial shape)