You can manage your Star card quickly from BT Pay. 

In the 'Credit info' section you can see the amount you need to deposit to pay your monthly obligation and you can pay it all from the app, without trips to the bank. 

In addition, you can choose to have an automatic payment (minimum or maximum) on the due date (25th of each month) each month, and if you have already deposited part of your monthly obligation, see how much you have left to deposit.