I've had Now Super Fibre for a few months now, and this problem has persisted.
Across EVERY independent check of connection speeds I have 28 to 34 mb/s download speed and an upload that is more or less exactly what I pay for. However, my guaranteed download is 52.8 mb/s.
The Now tv website tells me I am getting 70.1 mb/s. This is a flat out lie.
These tests are made on a pc, with no other devices linked to the wifi, via an ethernet cable to the router that is on top of the pc. EVERY SINGLE ONE, other than Nowtvs website, give a download of around 30mb/s. With an actual download speed on steam and the like of 7mb/s.
We cannot watch two HD streams in this house without buffering either.
So either NowTv is lying about our speeds or every test I can find is.
What can be done about this?
I wouldn't have thought that "the router that is on top of the PC" is the best place for it. Is it connected to the master socket and if so have you also tried at the test socket?
Subject to that, contact the Broadband support team as indicated in this help article:
Definitely give them a call. The Now site is probably reporting your sync speed, not your download speed. Also you should be able to see your current sync in the router.
On a wired connection you should expect a download speed approx 10% lower than sync, so in your case about 63Mbs.