Battle.net account

It depends on how the accounts were setup, Rowdarn. If your son has his own account, that is completely his own, then Billing & Account Services should indeed be able to move the account to a Battle.net account that you can have setup for him. It gets a bit tricky if you share the same account and both have characters on that account. I would advise contacting Billing & Account Services when you have the time:

Webform: http://us.blizzard.com/support/webform.xml
E-mail: [email protected]
Phone: 1-800-592-5499

Hours of Operation: 7AM to 8PM PST— Wednesday through Tuesday

Q u o t e:
we do have two accounts but both under my name his account has all his characters and was made when he was under18

That's perfectly acceptable, Rowdarn! As Pahanda mentioned above, you may want to create the secondary Battle.net account in preparation for having your son's account transferred over to it. In the event that you have any characters that he may play on your account, it would be a good idea to transfer it over before you contact Billing.

Once you are ready for the transfer to be done, use the contact information I provided above and get in touch with Billing & Account Services. Calling them is typically the quickest way to get an issue resolved, but they tend to see I high volume of calls, and it can be difficult to get through at times. If you have the time to be persistent, then you may want to simply continue redialing them until you get through. If that is not an option for you, then use of of the other two methods provided above. :0)

Q u o t e:
Thanks for all the info you have been great

Sure thing, mate! :0)