GoneTomorrow: That spectrum shows some serious wiring issues not related to the distance from the cabinet
About the splitter; that could be correct. For VDSL a 'master splitter' is installed. It is not visible as it is usually installed inside your ETP (Telecom/Chorus box on the side of your house where your phone line comes in). Were you present during the installation? The technicians should have spent a bit of time installing a dedicated VDSL line from the master splitter to the jack point where your modem connects.
If this was not done, it will certainly be the cause of the bad graph, and your slow speeds.
Oh dear! Perhaps I should get in touch with Snap.
The technician didn't go into the details over what he did, and I didn't actually ask.
The technician simply came over and hooked up our modem and then left...