Uber does not allow multiple accounts from a single device.
The most you can have is 2 accounts on one device, that too, not under the referral code of your account.
So, technically, you have violated their policies which resulted in your account being banned.
How to get it back?
write an email to support and state the facts you have stated here. Attach a photo of an ID proof and request them to give you access back. Be polite and request rather than demand.
How to regain access of your Uber account once it’s disabled – QuoraJanuary 3, 2017