how long You are EE customer?
I have been with BT for over 3 years but recently moved to EE, and for them, I am virtually NEW customer without history on the account (which is technically speaking true, whilst my BT account was terminated, and new EE account is just NEW), and have actually restriction only ONE Mobile and ONE Broadband service at a present moment, and need to wait 3 or 6 months to be allowed to use the website to add more lines.
However, Guides on 150 MIGHT (or not) help to add the product You looking for, if that's is a service from EE
