I am happy to hear about the referral contest BUT you need to be Premium to honestly win anything.
So how many places is there gonna be for winners, places? I think you should just reduced the ores earn.. not completely take it. I mean round it down to 100-1000 off percent on the ores. Example 50000 iron to 500. Just a thought.
Being premium will definetely be a bonus since you get referrals for free. However, the current top referer is not a premium member as far as I can see right now.
And reducing balances could have been an option yes, but I have already removed it entirely by now. You will start earning them back again soon enough though.