Your electricity supplier should be able to assist. (If that meter is the one which they use to work out your bills, they'll act very quickly if you tell them it's going backwards!).
If your company are obliged to get it replaced themselves, then the best action is to look under 'Electrical Engineers' or 'Electricians' in Yellow Pages (selecting a firm who specialise in commercial work).
If your company employs their own electricians, they ought to know where to get a replacement meter anyway! If not, point them here:
http://www.apexengineers.co.uk/meter.html
Wherever you go, the replacement meter will be of the digital type as the old 'rotating wheeel' meters are now redundant.
Chris