Scars are the most difficult kind of tissue to change.
One of my employers used to let his dog trample me everyday. My arms would bleed and he would ask what was wrong with me. This left much scarring on my arms.
I still have some, but over several years I have been able to improve them markedly by using abrasive hair removal pads. Essentially using a crude macro-dermabrasion technique.
I am sure that this technique could be combined with others, such as topicals (vitamin c serum?), to provide a slow, but persistent solution.