The agencies, which are incumbents on the Galaxy advertising, media and PR accounts respectively, clubbed together for the pitch, against undisclosed agencies.
The chocolate brand has done little in the way of digital marketing to date, although it has a sizeable following on its Facebook fan page.
Galaxy is currently supporting its on-pack promotion 'One Million Moments', on Facebook and its brand website, enabling individuals to enter a promotion code found to win a range of prizes.
The appointment comes as Mars is planning to reintroduce its classic "Why have cotton when you can have silk" strapline this year, after an 11-year hiatus.
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