You're nearly there too!
They don't do it though, probably because 10% is the weight where a lot of good has been done, apparently it's when your BP shows reductions and you have a lot of health benefits.
Incidentally, it always seems to be when people start to notice weight loss too.
How long ago did you get your club 10? The voucher should come with a letter from SW and you use it in 10 weeks time. YOu used to have to fill a form out but it's all done automatically now everyone has the computerised system.