I have the same problem, signed up with BT august the 2nd, with a promised speed of between 21 and 29 mb. After more than the 10 day period, i only managed 16mb, i contacted bt and an engineer came out, he confirmed that the maximum on my line would be 21mb. But I suspect to get this, he reset the ports in the cabinet before the visit to get it, as within hours, the speed dropped back to 16 mb. Since then I have had 3 more engineers visits who have all confirmed the same maximum speed, 21mb. After the last visit, I connected a third party router, Netgear D6400 and the speed bounced up to 22.8mb. I had this weekend away and when I came back the speed on this router had also dropped, but only to 19.8mb. So I thought I would try my smart hub 6 again, sure enough it has synched at 16mb and that's it. I'll give it a few days to settle down but I don't expect any improvements. The problems I have is if I complain, the only option is to order an engineer, which would be number 5,who then gets the speed back up to the promised minimum. But after 4 visits already, I cannot keep doing this as I can't afford any more time off work!