Also an update from me (I was also due to fly out for the F1 in Hanoi)..
A couple of days ago TravelUp cancelled my flights and said I need to refer to my original ticket number should I wish to make a new booking.
The flights were not cancelled hence I believe this is why they did not offer a cash refund, but if I can get booked onto something else soon then I don't mind. If not then I'll push for a cash refund.