@Harry_C if it is a utilisation issue, which it does look like from the BQM and also there have been numerous complaints in the past from users in the Bromley area about this very same thing, then I’m afraid there is absolutely nothing that an engineer visit will achieve. Think of it like a road which gets congested because of too many cars using it a peak times, there may be a couple of small potholes in this road which can be fixed (equivalent to an engineer visit), but this doesn’t help with the congestion. The problem is not with the state of the road, but rather there just isn’t enough road.
The road needs to be widened, or in this case, more capacity put in, but this can (ie is) expensive, and sometimes just isn’t realistically possible, just like you can’t always just widen a road if there isn’t physically room for additional lanes.
Not any of this, admittedly brilliant😉, analogy helps you in any way shape or form, other than to set your expectations to see it as not being a ‘fault’ that VM can ‘fix’ - at least not in the short term.
OK the obvious answer is to leave, but you have already stated that this isn’t really viable as the best speeds you can get via OpenReach is too slow for the rest of your household. But how about, depending on how seriously you take your gaming, you have a second internet connection, which is purely for gaming? Despite what many think, online gaming does NOT need particular fast speeds, the latency and jitter are far more important. It may not even be too expensive, at least for the initial contract term, and depending on exactly how much you fancy getting into the weeds with routing tables, you could even have a setup which automatically uses the VM link for some tasks and the alternative link for others (gaming)!
In fact you might find (if you experiment) that your household can indeed function quite happily with a ‘slower’ connection - you will be surprised how often people overestimate what they ‘need’ - in which case you can give VM notice in a month or so.
Something to consider, anyway.