cancel policy within 15 days of purchase & get refund (excluding GST)

I purchased Policy (INDIAFIRST LIFE GUARANTEED PENSION PLAN) by paying 1lakhs 2 days ago from (Indiafirst life insurance). but after calculation I feel it is worthless. so now I want to cancel policy and get refund (excluding GST). I think there is 15 days free look time. so can I get refund? Agent is denying to cancel the policy. She also said If you don't want to pay you can skip 2nd and 3rd installment but you will get your 1 lakhs back after 3 years. About Plan: pay 1 lakhs for 5 years (total 5 lakhs), after that you will get 35000 yearly