Billing charge

Hi, when i start to use Xfinity last year my deal was 63 and if i pay by checking account will be $53, i did ask for regular mail to change my Driver License and it added up $2 so $65. Since I didn’t ask for regular mail anymore and back to paperless my bill still $55 instead of $53. I just want to know the reason, it been 6 months and isnt change back to $53, please explain, thank youu.