Capital One 360 No-Fee Banking Internet

They didn't close your account for "no reason", they gave you a reason.  You don't have to agree with the reason, but they did give you one.

You can complain all you want that the reason was wrong, but in the end they have a right to close your account at any time and for any reason.  They could have just said they don't want to do business with you...and there is not a single thing you can do about it to force them to allow you to have your account back.

Before you say it, yes when you opened your account this is something you agreed to when you said you read and understood their terms and conditions of the account.   This is also how every other bank works as well.  

As I said it doesn't matter the reason why they closed it, but it is very curious as to why they would think you were using a voice modulator.  I am sure there are things to this story that you have intentionally left out.