BRP Collection for children

[nagarjuna04]

Hi All,

My family came to UK on Tier 2 dependent Visa. Their Vignette is expiring on 7th Feb 2018.
Today, We went to respective post office to collect BRP for my Wife and 2 children. They have given my Wife's BRP Card and they haven't provided the children BRP's and they mentioned that I need t get a 'responsible adult' letter from Home Office?

I have submitted a form using the below link.
https://www.biometric-residence-permit. ... se/arrange.
Please let me know whether above form is correct form or not?

The link description says that they will process the request in 5 working days. but we have just 3 working days left for the expiry of Vignette.

Can someone please advise on below?

1. How many exact days Home Office takes time to process my request?
2. What are the next steps that I need to take if I don't collect BRP before 7th Feb?

really worried can someone provide any suggestion?