Well I'm wondering why people haven't discussed that the major change this Contest is not the low codes, they've happened before, it's the fact that the Contest codes appear to be geo restricted to the country in which the game was registered.
So, my observation is that if one plays the UK version of the Contest then the UK is the only country that those codes work. Can people playing the Contest in the US and Canada (because the UK, US and Canada are the only allowable countries under the rules) please confirm that that is the case. That is, try the code on books in India or Mexico etc
What that means for all of us is that if we can't use the codes in non publisher restricted countries we all go back to being 'captives' of the publishers once again. Yucko!!!!
Good news:
I tested a Comeback 30% code I recently got for my US account - and it works on publisher discount eligible books in Aus, and any book in India.
Phew