Changes to Guaranteed Velocity (Platinum) Intn’l Reward bookings

Hello AUSBT readership,

Does anyone have experience making changes to a VA reward booking made under the guaranteed international economy reward ‘benefit’ made available to VA Platinums?

It took me literally weeks to get it booked (inclusive of almost 2h of futile debate with several VA team members telling me they were unable to deliver on their ‘guarantee’ by all means of excuses (and I mean every excuse in the aviation book)), but was finally satisfied of this problem by writing a letter to VA customer support after which, miraculously, my booking was able to be made.
With this in mind I am hesitant to approach customer service with this question as I expect to be similarly stonewalled, and there are no T’s & C’s relating specifically to changes to these bookings.

Thanks in advance for your help!

I believe any changes will be subject to the availability of reward space. If there are no economy rewards, it would be unlikely for them to be able to change it.