Indeed, hurry hurry and make sure you get an agent who knows what they are doing. They should -mail you a form and you fax it back. If the CX-Amex deal ends on 31/3, then Amex will likely have little scope to correct if an agent messes up.
I meant to explain clearer in my earlier post that you can be 99% sure to not lose a cent of value if you use your travel credits for flights. Hotels, Amex do not seem to get the most competitive rates but flights they have always been excellent in booking eactly what I have wanted for the same or less than the best afre I have foudn on the web.
Oh and referral bonuses are very sweet and Avion will give you nothing to compare to that!