Got the email last night as well. I had an existing JASA booked so jumped on the phone first thing this morning to cancel and rebook to take advantage of the offer. Got passed around to 3 diff sections and after over an hour on the phone, got my old JASA cancelled and rebooked at no cost at all. I was told at one stage that the cancellation will incur a 5000 points but I asked her to check the T&C again and she was able to do it without the penalty.
I just went through a similar experience. I wanted to cancel 2 mASAs and book another one in their place. I'm not sure if I got the premium desk when I phoned or not but I was told quite clearly that I could only get $$$ back for cancelling an ASA of any type. That's similar to cancelling online. I told her that I didn't think that was the case and that I would go away and check the T&Cs.
Having done so I was convinced that I was right. For my own booking the relevant terms seemed to be:
"
15.6.1 A refund of an Any Seat Award will only be made in accordance with the applicable Fare Conditions and these Terms and Conditions, and the following provisions:
(a) If a refund is requested prior to travel commencing, and the money paid to obtain the Any Seat Award is equal to or greater than the cancellation fee (or refund fee) specified in the Fare Conditions, and the original Any Seat Award booking was not made on jetstar.com, then
the refund of the Any Seat Award will be made by re-crediting Points redeemed to the Member's account and refunding any money paid to the Member's Accepted Payment Card, less any applicable cancellation fee (or refund fee) set out in the Fare Conditions."
I phoned again and spoke to someone who was definitely on the premium desk, agreed with my assessment and knew how to book mASA's too! He cancelled both bookings teling me that I'd get the points and cc refund in 72 hours and didn't even mention a cancellation fee. He then went ahead with the new booking of a mASA even checking that I had registered for the 50% offer through the email before he processed it. All this in less than 20 minutes. He told me that there 11 people on the premium desk at that time when I mentioned that I'd been waiting for a connection for a while.
In the end, excellent. It certainly paid to HUCA.