To be fair, IS Fibre as a backbone doesn't differ from SAIX Fibre.
IS gets a bad rep about latency because of their satellite-based accounts, but the 626 package clearly uses the IS Fibre (which is over the SAT-3 cable, exactly the same as SAIX/Verizon unshaped to my knowledge).
I do not have a 626 account to verify this, but I'd bet it uses the same backbone as the IS Semi-shaped accounts. The latency difference might be a load issue on IS's side or a temporary problem?
In any case, if you had a problem with the backbone of the 626 account, you could've called/created a support ticket and queried this beforehand. As you state, they don't specifically tell you it is on the IS backbone, but they don't claim it to be SAIX/Verizon based either. This would be an assumption on your part? =P
When I phoned and asked about the product (yes I still use a landline) I was told it was exactly the same as normal unshaped just with a no daytime use policy.
Go on their site and try and find the differences between normal unshaped and 626. The only thing they mention is time restrictions. I am joe public not an IT expert. They sold me crap bundled into a packaged that clearly states it is faster than shaped. Well my telkom shaped gave me better pings and ironically was far more stable.
So forgive me for catching them out as blatant liars.