The thing that always baffles me with this one is they know there is a problem and they keep banning people who try/do it. Why don't they just fix the system and close the loophole?

Surely that would be much easier for everyone.

It's a joke that they send you a link to a promo and you need to enter your membership number and a code. They have sent you an email with your membership number imbedded in it why do you need to enter things again? It should be a case of one click and you're registered and their system picks up the promo
You have been targeted for.