Not if you paid right after NS sent you the email with instructions on how to pay. You could contact NS customer service to verify if you're unsure, but if you haven't received an email stating that your invoice has been transferred to a debt collection agency, there’s nothing to worry about.

Welcome to the NS Community, Sawsan.

If you've paid before the date on the reminder you got, with all the necessary details, then you won't be charged extra. Of course, if you want to check if the payment has been made in time and came through correct, you can always contact Customer Service.