If you feel you have been incorrectly banned you can dispute any action against your EA account by following the steps in this article:
https://help.ea.com/en/help/account/information-about-banned-or-suspended-accounts/
That really stinks.
You can definitely try to contest the purchase with Google Play, or your CC company.
I would also suggest that, if you can stomach it without blowing a gasket, you try one more round of escalating the issue with EA CS and try to get a dialogue with a manager.
Patiently explain the situation that you did nothing wrong, you are now banned, it was investigated and they are keeping you banned for no reason, etc. etc. Maybe you can at least find out what they think you did.
I will say that I'm not sure that your purchase is directly relevant to this - in other words, the fact that you bought Madden Cash is not in and of itself a reason that they should unban you if in fact you are a bad guy and violated the TOS. (I'm not saying you are at all! I'm saying that the purchase of Madden Cash doesn't actually relate to clarifying your banned/not-banned status.) But, if after even escalation of the case to CS managers they do end up keeping you banned, you should be able to argue successfully for a direct refund from EA of what you purchased.
