I've been in this situation since 3rd March! When BT failed to get me connected after 6 weeks (and 2 MACs) I tried Plusnet with a 3rd MAC. They are getting similar responses from BTW. The MAC is usually reported as the reason for failure to place the order.
BTW "have acknowledged there is a problem within their systems and are working on a resolution for this".
They have been working on it for 11 days so far. My 3rd MAC is about to expire.
Xilo C&W LLU, Netgear DG834 PN, St Ives Cambs