Just rang Adelaide Hilton, who transferred me to Member Services as my request online for credit hadn't been processed. Got put through to the Diamond desk, so wasn't complaining.
Strangely, they had no request, so have submitted one for me. I'll give them 14 days and see if it's been processed.
Also asked them for a FastTrack back to Gold. She put me on Hold and came back after a while to say that they had upgraded me back to Gold, without the need for a FastTrack. Just logged out and logged back in and sure enough - HHonors Gold VIP below my name. Woo hoo
With 2 stays at MEL Airport and MEL Southbank next week and a trip to Perth next month, should get me on track for re-qualifying Gold for next year (very important, given our 6 week trip where we'll be burning all my points on award stays - plus a couple of paid ones).