I have been with bt for a few weeks and my speed its not rear my estimated speed of 50 mb.
BT support havnt been very helpful, told me it will improove over time.
Any help would be great.
You have something called DLM which monitors the connection of the line, and will limit the speed on the line untill it becomes more stable.
Leave your hub for a week and see if the speeds increase (or in my case, if you have a old openreach modem, its white with openreach on the top with the 4 lights) then plug that in and use that (if you have another router as the HH6 5A doesnt support WAN) then maybe that might free the line and increase the speed as some users have reported problems with the HH6.
Let your line stabilise, and if the line remains the same, it might just be your line, or the port you are connected to, like Webby said, only a engineer will be able to tell you this.
Also make sure with BT what 'actual' infinity package you have been sold, as for lower lines i do know they still sell the 36mbps package (however this wouldnt make any sense or match up with the BT Wholesale checker)
Leave your router to sit for a week and then see how the stats are