The only way to request a refund is via a ticket. If you’ve been told that they’re not going to provide a refund (which is standard when the game time has been played), then that’s your answer.
The EULA (or TOS as you put it) has not changed. Most of their policies are not spelled out in the EULA, they’re provided via support articles etc. In this case, they made an announcement regarding their change in policy. Previously, they did not support software that allowed multiboxing. Now, they are no longer allowing it.