Paid hosting will remove third party ads from other services registered under the SAME account but doesn't give a full upgrade. You will still see Bravenet branding and offers of Bravenet services.
If you are seeing non Bravenet ads then raise a support ticket. To remove Bravenet branding you have to upgrade the service to its Pro version.
If you have free services under a different account to the one where your hosting is registered then they will keep the ads.