Is there any shampoo which treats & really helps for greasy hair ?

A few: Most shampoos these days are mild. They are mild because people color their hair, do heat treatments, straighten, blow dry , etc. Older shampoos such as prell were much harsher but got rid of all of the oil. Look for a shampoo for oily hair. The best person to ask maybe your hair dresser. Don't get one for fine, dyed or chemically treated hair. Try dial soap if your hair is really oily.