Click on the Support icon which is available in the lower right-hand corner of almost each screen
in the application, then at the bottom of the screen you will find "chat with us". 

You also access the chat as follows: click on the person icon in the right top corner of the main screen -> scroll down and select "Support Centre". 

Write down your question and then click on the small yellow icon to the right of your text. You can also attach files to us by clicking on the paper clip icon to the left of the text.