It's more likely a downstream attenuation of 31dB and a target noise margin of 20dB which is throttling speeds.
Regarding the 10 days training period. this is what I can see in Mysky
Testing on your broadband connection began on 29/12/2014 and will be completed within 10 days.
You may notice some variations in your broadband speed and this is normal. We are aiming to give you the best quality experience. Please leave your router on during this time.
I have no idea why testing started on the 29th as I have not seen any problems and certainly have not contacted Sky!