So just an update, the Marriott backoffice team (the ones that look after missing stays reports) have actually done good, i was a little harsh earlier. They chased the W - who sent me my bill, which i gave back to the backoffice team who have now done the work to add the missing stay, it did take a few attempts, but in fairness i think the issue was with the W, not the missing stays team. Yay platinum here i come.