If they were all in your brothers name, then it shouldn't be an issue.
But even still, I'd call billing and see if you could change that.. point out you were the sole owner of the accounts from start till now, and have been the only one to pay for them too.

If some were in his name and others were in your name.
Well, that's a reason for them to ban, as sharing accounts is against the EULA, with the exception of a parent/guardian who shares with their minor child.
Even if that was the case, if you're the sole user of the accounts then call billing.

If you share with your brother, and live together (same IP address), you might be able to get them to transfer them all into your name.