How could i change this habit of my 3yr old child?

my son drinks formulated milk in bottle but he's going to be 4yrs this year.he also has gastric problem and asks for the milk bottle even if bored or when watching tv.i try not to give but he will make a big fuss and have to give.minimum he takes 3 bottles per day.he wont drink any type of juice or any other drink,just milk.how could i change this and is formula milk for 3yr old ok,the milk packet says 1-3yrs old.what is a good brand of milk i can give to him instead?