According to this article
The failed T4000 was a test of the TVS system. It failed to ignite due to a valve. The planned impulse time was just 10 seconds.
The current plan has six stages, called VEX. Only four are talked about and I'll correct some mistakes that I'm assuming they are makings.
VEX 1: One stage. Apparently it will weight 1.8tonnes and have a 4tnf engine (the articles states it the other way around, which doesn't makes any sense). Apparently is a 30 seconds mission with an optional additional 30 seconds. Budgeted for 2013/14.
VEX 2: First Stage will use 3 x 4tnf engines. Second Stage will use a 4tnf engine. Budgeted for 2014/15/16.
VEX 3: One 30tnf engine. Budgeted from 2015 onwards.
VEX 4: One 30tnf engine.
VEX 5: First Stage 3 x 30tnf and Second Stage 1 x 30tnf + RSC (new development). Apparently it will stage at 80km.
I've mixed the information on the article with the information from the Budget Office
. Just download the Excel, items 57125 (VEX I), 57126 (VEX II) and 57630 (VEX III).