Orange Minimum speed to provide Broadband

Now here is a new one ( I think). I have 2 phone lines at home, 1 already enabled with broadband at 1.5 mg ish with BT, as we live in a rural area.
As I have a number of Orange phones, on contract, I thought that I would take advantage of the free Orange broadband deal on my second line, as the kids do tend to slow things down when they are online at the same time.

Anyway, DAKS removed from line, e-mail name written down ready etc etc, call Orange.'Sorry Sir, your 2nd line is only 500 kps, you cant have broadband on there'

Now BT & other suppliers are happy to charge me and make provision , but not Orange, so is there something I am missing here?

Orange's equipment (msan in exchange) is pants.