We've had problems in the Trotts Hill (Wisden Road, etc.) area for two years now. What part of town are you in? Do you get full speed at off peak times (Silly O'clock at night.), or is it slow all the time? Do you notice a drop in speed between 4PM and midnight? Loads of questions.
Sorry to hear you've been getting poor speed. I've just checked your connection and can see no issues from here. Your power levels, SNR and area contention all look healthy even at peak times. I can see you're currently using modem mode, do you have another router connected? If so could you try a connection directly to the hub while in modem mode and see if your speed improves?
For some months now I have been noticing continual buffing when watching Iplayer and ITV hub or music radio stations and at times the web just seems to despair then come back. The whole Internet connection doesn't feel as solid as it did 12 months ago!?!
Supper Hub2 in modem only mode, linked via CAT6 cable ASUS AC3200 router.
While, of course, there can be other reasons, in the light of VM's current practices it's hugely valuable if everyone affected by speed issues go to https://www.thinkbroadband.com/broadband/monitoring/quality then register and set up a monitor. Leave the VM modem on for a few week days then check the BQM graphs - oversubscription issues can easily be spotted here e.g. regular increase in the evenings (did you see BBC Watchdog last week re VM? if not check it out on iPlayer!). Additionally, record some speedtest.net tests in the morning and at night, particularly around 7pm - 11pm.
If you are suffering from oversubscription then get straight on to customer retentions - no one else! - complain strongly, demand and get a proper bill reduction (not their £10 standard!) and mention that unless this is fixed quickly you will demand a Deadlock Letter and forward this as part of a full complaint to CISAS (VM's only ofcom-approved dispute regulator).