Charlie - no apology needed.
Notices are served as per the register entry so they should look at the register for AA68827 - Pilgrim House, High Street, Billericay CM12 9XY
There's no 'reminder' corres issued to them. If they have not received the notice or they have failed to keep the register updated re their contact details then they can
get in touch as appropriate. Doing so is likely to trigger a re-issue and the timescale reset accordingly