I have a account set up because I use it a fair bit in the works/company van. I then got 3-4 fines come thru in one go, phoned them up and explained this isn't possible as I have a automatic top up on the account. Turns out when my bank card expired and I got a new one I didn't update the card details for payment to be taken. I ended up having nearly 40 unpaid crossings. I understand that it was my fault but what did annoy me was that they email me regularly but never once emailed to say they couldn't take payment.