Postal Application change to Priority Application-?Possible?

[Lavans]

Hello,

First time I am using this website. It looks extremely useful. Dont know why I havent seen or used this before.
I am very desperate for advice and help.
My situation:
I have applied for a Tier 2 PBS Dependant Visa Extension in June, completed online and submitted by post. Completed the Biometrics 1 month back in July. My husband has an ILR through Tier 2 PBS Visa 5 years route.
I havent received my Visa yet.
Its still within only 6 weeks since my application date.
I am starting my new job in 3 weeks time. Need my Visa before that.
My question:
Is there any way to change my postal application to a Priority one? To try and get my Visa early?
Would be extremely grateful for any help, advice or suggestions.

Thanks a lot.