First let me get this off my chest. Everything about your account structure web ids etc is so confusing and counter intuitive it seems like you purposefully make it hard for people.
I have a WEBID with 2 accounts (dont ask me how that happened). I need to add another account and cannot find the button anywhere in my control panel to add a new billable account to my WEBID.
NOTE: All accounts (services) will be billed to the same person and credit card.
I want to give you more money please help me before I come to my senses.
We're just customers. You should contact support.
Note this quote from the TOS, which you might also want to ask them about before doing anything:
Maximum savings promo code: MaxSavingsAtDH