I think you need to stamp your feet a bit more with them. The dispatch day is clear, but the delivery date is an estimate.
For them to say that the PC is not yet built is a disgrace after being given a dispatch day. Looks like they have sent yours to a disatisfied customer and are doing you another one.
You should write to them and demand a reply within a reasonable period, send it recorded.
Contact your card company and explain the situation. They will mark Mesh's card.