Yeah I'm having the same problem. I applied via velocity 28/02/14 received the email it had been completed 22/03/14 however it did not reflect on my account. Called last week and was told they had to raise a case and wait a week. Just checked my account now and it says I am gold.. how they came up with gold I have no idea as I don't have enough stays for gold and I am VFF plat.
This is becoming frustrating, as writing above I decided to call, they said when I spoke to them they said I am a virgin atlantic gold member, where the last person I spoke to got that from I have no idea. As I specifically said Virgin Aus Platinum and I wanted Diamond hhonors. The person on the phone was adamant the last person I spoke to got it correct and I am supposed to be with gold. After pushing harder they said for me to become platinum I was given gold and need to complete 4 stays before I would be awarded platinum. After pushing even harder they finally caved and said they would raise another case and I have to wait another week to become platinum. I hope they sort it out in time as I have a stay (not this weekend) next weekend.
I know its a "benefit" not a privilege but it still is frustrating been told you can get one thing, but it being so hard to get.