What should I do about my marionette lines (young person)?

I'm really sorry that you have not had good results thus far. However, the kind of marionette lines seen in the photos are routine and fairly easily treatable issues in experienced physician injector practices and are treated practically every day. What I can say is that very likely either the wrong filler was chosen for the job or the wrong technique were chosen for the jobs was used. If the injector used an ordinary (non-robust) filler for the job. That could be one reason. Or if the injector merely "chased after the fold" by injecting directly into it, rather than checking to see whether the cheek needed to be augmented first instead, then this may be another possible explanation. And a fat-dissolving injection had little chance of working, since the problem does not result from excess fat in the region, but from the loss of the supporting tissue infrastructure above and to the sides of the marionette folds themselves. It would seem wise to make sure that you are consulting with a board certified cosmetic dermatologist or other core aesthetic physician and to ask to see his/her personal before and after photos before agreeing to any treatments. Hope this helps and best of luck.