Does the HH allow you access to stats since it looks perhaps as though the modem is only synching with a 40Mbps limit on the line, which could be a negotiation error? (I'm on IDNet's up to 75Mbps FibrePro and my Fritz only syncs with a 40Mbps limit at the DSLAM, although the reported attainable rate is over 45Mbps). In my case I assume though that it may be a conscious restriction by BT due to the nature of the local loop.
Many of us have found sync falls on the upstream on the 7390 (not the later 7490), usually dramatic though like in my case from 6Mbps down to 660kbps, due to changes made by BT in local cab firmware. (Most happened in November, though if you haven't resynced . . . ). AVM have some beta firmware to deal with that issue, but only supply it by request on a case by case basis, if you're lucky.