They have exceeded 21 days turn around time which they promised regarding my late mother's tax number reactivation

They have exceeded 21 days turn around time which they promised regarding my late mother's tax number reactivation.its now going for the 2nd month and nobody cares to assist us with the matter. We have been phoning continuously but to no avail. It's really frustrating because we need to make a claim to one of the financial establishment. They are dragging the time.