Is Voluma difficult to dissolve?

Last year in April I had 2 syringes of Voluma injected into my jaw & chin. I went in to have it dissolved, but it's still there. Is Voluma just difficult to dissolve? Is there any chance that my body just built up collagen in my chin and there's no filler left to dissolve? And last, would it make sense to go in for an appointment again to have her try and dissolve the rest of the filler left, or how long would it take my body to break it down on its own? I really just want it gone.