Here is a briefing about Amazon Prime refund policy. There are four conditions for cancelling Amazon prime subscription. 
Cancelling within 3 business days of signing up for free membership:
 If you cancel a prime membership free trial within 3 business days, you get a full refund. However, Amazon will charge you or withhold from your refund the value of prime benefits you use in these three business days. 
Cancelling any other time: you get a full Amazon Prime refund Policy,  if you did not make any purchases or access to prime benefits since your sign up.
			
		