Nothing to do with Niki, he doesn't do any of the admin/booking side of it. A week i'm guessing was actually 4 working days with the bank holiday, and if the guy doing the office/bookings has been off and is playing catch-up....
Also Niki's Facebook profile suggests using workshop@r-techpower.co.uk so maybe try that?
I'm not saying it's acceptable, just providing possible reasons. I know i would be the same in your position. Give them a call Tuesday morning first thing