How Can Chronic Face Nevi Be Treated?

I have lots of dark spots on my face. I have tried Allopathic medicines & creams & also Sal peel trearment from Kaya Skin clinic, but none of were of any use. Now i am thinking of going for Laser treatment. Please help & guide me. Also let me know the laser cost per sitting & where shall i go for this treatment in Kolkata?