When I had my original FTTC install (Plusnet) I was quoted 32 Mbps. Got over 36 on the install day but lots of problems since - even down to 16 Mbps and it settled at around 18.
Was going to write to CIFAS but just before I did I looked at the Checker and BT had 'adjusted' it to max of 21.1 Mbps !!
Is this worth pursuing ?