The 3 free minutes feature applies to any chat session you have with an advisor for the very first time. After 3 minutes, the session will automatically switch into "Hire" mode and you will be charged for each additional minute according to the advisors' per-minute fee. If you decide to contact the same advisor a second time, your session will go into "Hire" mode the moment connection is established.
Please note that when you start your session there is a very clear note at the bottom of the chat suite which clearly states that the session will automatically go into hire after the 3 free minutes have elapsed. Please be advised that you as the client are given the "Quit Session" button if for any reason you do not wish to continue with the session.