CC- actually this is ok. This is considered an upgrade. When you upgrade to reseller you have to sign up again on the website, as you've done already, because your account has to be placed on a reseller only server.
Then we move your files over from your shared account for you, and cancel the shared account. Just stay on your current ticket and it will be sorted out fine.
At first we were not allowing this, but then we ended up changing the rules.
The major thing that is not allowed is canceling an existing account, to sign up for the same exact plan again for that same domain.