Indian Railways — behaviour is not good of shopkeeper on plot no 3 in old delhi

Sir, i purchase one ltr water bottle and he told me price 20 rup. I told him that water bottle price is 15 rup why i will give you 15 rup than he told me to give 5 rup change with loud voice. I told to other person to take his 5 rup of water bottle which purchased by him then shopkeeper says why you are interfarring with other matter.
This matter happened in old delhi plt no. 3