Change in work address on Tier 2

[Kishorbm]

Dear all,
I'm currently on Tier 2 visa and my sponsor has opened up a new office near my house. They want me to start working at the new office and are looking at changing the work address. The original Tier 2 approval letter which I got says Name of sponsor 'XYZ Lambeth Ltd' and the new office will be 'XYZ Maidstone Ltd'. It's same parent company XYZ but different branch which is a limited company in itself. I wanted to know who will have to make an application for the above changes, sponsor through SMS or me using any particular form?
My HR manager has send UKBA a message but its taking them too long to reply.
I'm due tor ILR in August this year, will there be any confirmation letter from UKBA about the changes as I would like to keep a copy of it to show it to case worker when I make my ILR application.
Thanks in advance.

[Lucapooka]

It's a matter for your sponsor ; you don't need to take any action yourself.