Visa Application Address - Mild State of Panic

I am in a mild state of panic! I sent all my supporting documents for my wife and step-daughter to:

PO Box 5852
Sheffield
United Kingdom
S11 0FX

Checking the Royal Mail tracking service it still says:

Tracking no. BH8xxxxxxxxGB

Your item was received by Sheffield City DO on 13-09-2018 and is due to be delivered today by 1.00pm

Have I sent it to the right address? Used Royal Mail tracker many times and it usually updates straight away.

I sent our application to that address and received the parcel back after 11 working days of the application - so I guess it is

Thank you zeija, when did you send? I just hope they haven't changed things yet again!

We sent it last March using Royal Mail Special Delivery...

I've heard some couriers don't send in PO Boxes though! What a nightmare

I used Royal Mail Special Delivery and have found that it has been delivered. The online tracking system didn't show this but when I called it was confirmed as delivered. Now to wait for the decision!

now just sit back and relax--theres nothing more you can do.

Online tracking doesn't seem to get updated in 'real-time' - our documents were delivered (& signed for) before 10am, but not shown as delivered until after 4pm!