documents returned to sender

hi all,

I have few very urgent questions.


I send my documents via special delivery for the renewal

And I posted to the address
UK Visas & Immigration
Home Office
Tier 1
PO Box 496
Durham
DH99 1WQ

If I send by special delivery, should I send to the above address or some other address?

Also, my visa expires in a week, so now what action should I take once I receive the documents? Will I have time to send them for renewal? Not sure when I will receive my documents back

appreciate any replies please.