If you haven't received a reply before the fine is due (28 days from the issuing of a Reminder Infringement Notice) it is a good idea to contact the authority again. Write or phone to make sure they have received your letter and ask them if they've made a decision about extending the time for payment.

If they have decided not to enforce the fine or have allowed you more time, keep the letter that advises you of this in case you need it later.

If you are told over the phone what their decision is, ask them to confirm it in writing. It is important to keep the letters so that if a mistake is made you have proof of what you agreed with them.