Melon's Unlimited service is a ****

Melon Mobile advised an unlimited calls service which to my surprise does not even exist, DO NOT SIGN UP WITH MELON. They are asking me to recharge with additional money right now. What is the meaning of Unlimited. These are the messages they sent me: "Unfortunately we are unable to assist you with topping up your voice minutes at this time. Currently your total voice of minutes for the past 6 days on trail is 500." + "The is a fair usage policy for every plan. You are most welcome to purchase voice top ups in the melon app for now and move to a paid plan that may best suit your needs." + "I am afraid you going to have to top up your voice minutes."