From reddit post.
Apparently, they not just did the mistake but have tried to correct that mistake by something it's unethical do to: manipulating the market when the real money is involved in it.
Sure, it's only a 'game"... That is making billions of dollars profit and that is also how much it costs it's customers in microtransactions.
And we know it will lead to internal company investigation and we are sorry message, and not in external audit of EA market manipulation practices.
And if you guys think you're geniuses for picking cheap heroes and then selling it for double the price because of the rebound - it's because EA price fixed double price for every last one of them at the same moment, helping people who got their hands on heroes for cheap coins to earn millions within minutes.