What can I do with a (partial) Z?

In December, I booked a Z class return LHR->SYD in the new year sale - being sneaky, what I actually did was booked LHR->HKG in January, then stopped-over in HKG (where I live) until March, when I had a family wedding in Sydney, which I used the 2nd and 3rd legs (of 4) for. Of course, given that it was a sale, I had to book specific dates in advance, and it's Z class so non-changable - I didn't really have any plans for the 4th leg, so I gave a random date of 21/7 for the HKG-LHR flight. I expected to let it lapse, since I had paid less than a regular LHR->HKG one-way and HKG->SYD would have cost.

In the meantime, things have changed slightly. A few days ago, my boss (also my cousin) took me out for a beer and fired me. I'm not overjoyed with that, but it's not unfair, things weren't working particularly well, etc. etc. I had been considering trying to get a few days off at the end of July to pop back to the UK, but since I'm now working 3 months notice ending at the end of August, that doesn't seem particularly sane. On the other hand, once I'm no longer working would seem to be a sensible time to take the trip...

So, my question is, what can I do with my partial Z, if anything? I know I can't change it - my main thought is to, if possible, upgrade it to something which can be changed, then change it. I just wanted to get the collective wisdom here, before spending time on the phone to VS in the UK (nothing against the local folks, but it's just so much easier to speak to the UK people) trying to argue it out.

Of course, last week in August is going to be a really quiet time for flights into the UK, right? [:w]

Just to reply to myself - I called last night and spoke to a very helpful - as always - premier team bloke. The short answer is that I can pay to upgrade my 1/4 Z ticket to a changable fare, and then change it, but the total cost is likely to be far higher than the cost of just buying a one-way ticket for the date I want, so there's no point doing anything with it.

Better for me, I think, if I can pull it off, would be to buy a PE ticket and upgrade it on miles - 10k miles for about 1500GBP savings, assuming availability etc.

For the 13.5k or so miles and the 5 tier points is it not worth making the flight and then getting an economy fare straight back the next day?

How close to making gold are you?

I would love it if it was worth it, but honestly, I don't think it is. At the end of July, I'm 13 points away from Gold - 5 points from this flight, plus 2 from the return would leave me 6 off. As it happens, I would quite like to go to Singapore before the end of July, and of course it makes sense to go on Singapore Airways, so doing that as a return business class would pick up the tier points.

On the other hand, I can go to Singapore on an economy, non-miles-earning flight for under HK$1400 (under 100quid at today's prices) which is about 10% of what the 6-point-earning business-class ticket would cost. And that's on Singapore, who are far from the cheapest airline in the region.

In other words, I'd probably end up spending at least 1500 quid to make gold, when I've already retained silver, and I don't think that's worth it...