I have just found out my old SSE Technicolor router, got my username from VF and connected it. Sync has immediately improved, but still not enough to get over the 55 guarantee.
Line Rate 13.53 Mbps 48.6 Mbps
Output Power 6.9 dBm 6.9 dBm
Line Attenuation 2.8, 28.1, 45.7 dB 15.4, 37.3, 57.1 dB
Noise Margin 6.1 dB 6.1 dB
Obviously the VF app won't now connect, so will have to go around the houses to try and get any info out of VF, let alone invoke the guarantee as allegedly you can only do it through the app.