Have you rebooted your homehub since the fault? If not, try a factory reset of the homehub by pressing a pin into the recess button on the rear for about 20 seconds.
Heard from the engineer that it turns out to be a card fault in the cabinet, or at least errors are showing there - for all I know the errors might be further back in the chain, that seems more likely given that there was a general problem in MK. ETA is something like another 5 days on that being fixed.
The engineers tried: lift and shift, changing which bit in the cabinet I was connected to, different hub, different white modem, their own laptop. Nothing changed the results which were: hugely variable download and uploads down to 1Mbps and up to 50, packet loss going upwards of up to 30% at worse.
Thing is, the packet loss being different at different times of the day, ie none at all at 6.00 am, and huge amounts at 8pm indicates to me that it's not related to anything in this installation, but a problem at a more distant point.
What's worrying is that the BT's hand-held equipment detects that the line is okay, is doing expected Infinity type speeds, so their tests must rely on the signal level of the line, perhaps of what is being reported by the equipment as to what the connection state is - what BT Openreach need to really do is use a PC, such as a laptop, and run speed tests, and packet loss tests and quickly eliminate things like the hubs and modems, by swapping them temporarily in - it takes minutes, and instantly eliminates all sorts of variables, yet they don't do it.
Sorry i didn't reply sooner but ever since my post saying my connection has been fixed, everything has been fine. Im getting the exact same speeds as before the fault (28 down, 8 up) and i am not having any packet loss or disconnects whatsoever.
I did notice last week (thursday i think) openreach engineers opening drain covers and playing with cables running all along buckingham road in bletchley, I have also had an engineer at the pole near my house (probably someone nearby still having issues)
I spotted a BT van visiting my neighbour's house... Yes it turns out that everyone connected to the particular card in the cabinet has a problem; some may not have noticed it, because at a basic level, you mostly get web pages up, although the download rates are all over the place.
So another engineer called today, second line support. But it all seems to be going nowhere, with no-one just getting an engineer to trace the fault from beginning to end. Sorry BT but this is just pure incompetence. They have (in theory) replaced the card in the cab, to no avail.
To me it seems crystal clear: there was an outage that took broadband down for a good many people, someone did something at the exchange, and messed up some of the connections, damaged something, or changed some protocol.
Why else would it be completely down for 2 days, then come back partially? The simple suggestion - find out who did what on Monday and Tuesday last week and check their work - falls on deaf ears.