You may have specified in the past that you no longer want to receive confirmations. To cancel this and again receive confirmation text messages, simply send the code C1 to 4411.
Have you not deactivated the confirmation option? Then you can still consult the status of your parking session by sending the code i to 4411. You will then automatically receive a text message with your current parking status.
You can, of course, always contact customer support for more information and further support.