Dark Spot & Pigmentation or melasma.

I am a 43yr.old Male Suffering from dark spot & pigmentation because due to excessive exposure in sunlight faces discoloration of skin colour of face,develop dark spot on face & forehead nose,for these under guidence of skin specialist doctor applied triple combination cream{Mela care , Avemom -HT}either these also uses kojic acid diplamate vitamin C{cream & orally} both arbutin glycolic acid mix cream from all of these got relief but it's temporary till then continue the treatment got relief when stopped asrises again same as previous.As I think the mistake done by me I was not any of the one treatment not  continue any treatment max.1--1.5month maximum.. Now request you to please advice me the best treatment option and guideline. For use & duration taken. Hope so you are reply with postive responce.