Well yeah, I hope I just had bad luck and it's not a quality issue indicator.. Waiting now for the invoice from Tantan and hopefully it gets here fast 
I didn't get any manual with the bike or anything, the only thing was that the expansion plug for the steerer had a QR code going to the specialized site with sl7/8 expansion plug instructions. I went with the SL8 manual as the bikes are pretty much identical with really minor differences.
The $40 for the new seatpost seems fair so that good news.
I will press for the installation instructions myself and see what they say, once I get confirmation that the frame is finished, I’ll update everyone.
As with my Venge, SL7, and SL8 builds, I won’t be using the supplied expander plug — I’ll fit a Carbon-Ti or Extralite expander instead.
I’ve already sourced some titanium bolt upgrades and a replacement front brake mount, as I’m aiming for a budget Weight Weenie build.
For smaller titanium parts like the seatpost wedge and seat clamp bolts, I’m using TAIMELI via AliExpress — they offer the same quality as TiParts Titanium but at a much better price.
And possibly Ti Thru axles if I can get a good price on Aliexpress also or maybe use my Overfast Axles and upgrade to TiMaster of the gen SL8, decisions decisions.
I’ll check if my Darimo post from the SL8 fits out of interest
I’ll likely use the supplied post, cut it down, and swap the fitting and cradle to save weight.
Trying my best to keep this build budget!