Snow travel - Demanded more than agreed package by travel agent

While I am searching online for a good package trip to kerala.,one agent came online and committed for *****/- for the whole trip of * nights * days for my family consist of * adult and * child..i have planned in ** days in advance .he has asked me to pay **% initially, after payment done called me and pay full amount of package due to high rates otherwise rates will increase.again I have paid *****.after complete trip amount of *****/- .demanded another *****/- to book for next * days of my travel and for cab booking. I have told why your charging more than package but he has confirmed unable to offer with in *****/- and travel agent replied if you want you can cancel the trip no amount will be refunded.after dine total payment of *****/-given mail confirmation that no need to pay single rupee.with in one day demanded GST amount of **% of *****/- which is ****/-same got paid due to black mail of zero amount refund if you don't pay this. For a agreed package of *****/- I have paid extra Rs.*****/-.need that travel agent should be punished and ensure no one should suffer