Cancelled Policy and NO REFUND!!!

A sales agent called me to take up a One Plan policy and was told that I can cancel within 30days cooling off period and if my account was debited I would be refunded. My account was debited and I cancelled the policy, I've sent through three cancellation letter and conveniently enough they only received the one that fell out of my 30 day cooling off period and now they do not want to refund my money. I want my money back and sorry to the agent Winston for calling to cancel because I can only remember his name.