This is a more concise version of events for those who don't want all the data, tests and pictures.
Full Report Here.
8th February. Used for indoor turbo trainer sessions. First battery lasted 7 hours. Replacement battery lasted around 5.5 hours.
With the third battery I did tests to make sure the ANT+ and Bluetooth were 'going to sleep' when the unit was not in use and concluded that they were, so something else is draining the battery.
22nd February. Meanwhile I had contacted stages Technical on and later posted a link to my blog report on their facebook page.
25th Feb. Stages' Evan Gaspar replies after reading my blog and says he will send out a new unit.
6th March Email from Saddleback saying my new Power Meter has been sent out.
11 March New Power Meter arrives, fitted in minutes. I will leave the battery in. Have an indoor session tomorrow and an outdoor on the 13th.
18 March After a week and several rides and workouts I used the Stages App to check the device and the battery was still showing full :) Happy days.