Worked fine for me.
Firstly make sure you are entering the code exactly and that it hasn't been used before or that you aren't trying to spend too much and you are in a supported country. Make sure you don't enter any trailing or leading spaces if you copy and paste.
Then if it still fails try calling the sales team http://www.sonos.com/en-gb/contact
https://sonosanniversary.com
Arc + Sub (Gen 1) + 2 x Play 1/ Stereo Play 3s/ Era 100 Stereo in Kitchen, One Stereo in Bedroom, Play 1 stereo pair in Study, Play 1in Bathroom, Sonos Move 2