Firstly BB, what speed do you get when using a computer that is directly connected to your hub via ethernet? (ensure wi-fi is turned off on the computer)
What hub do you have? is it new? Is it new cable to your house? is it new internal cable? Log onto router & see what speed it says (tools - network status)
I had a new cable from street box, new internal cable (I ran it myself) and ensured the terminations between exterior & interior cable were 100% perfect and waterproofed to stop issues in the future. Some flats may have pre-installed block wiring, or re-used old cables from a previous occupier for example, and may have unseen damage causing issues.
Until the first part is sorted, it is pointless trying to get good wi-fi, as that will never be faster than that of an ethernet connection. Personally, I have always found wi-fi from any provider to be quite limited in range. To be fair to the suppliers, they are restricted to the radio signal strength they are permitted to send from the router and cannot control the environment, e.g. concrete walls, densely populated area with all wi-fi channels in use by other providers.
VM do not, and never have guaranteed Wi-Fi speed or coverage.
The problem with Wi-Fi is that it can be brilliant at breakfast time and useless by lunchtime and you haven't changed anything, BUT, something, somewhere has changed, then you can spend hours and even days trying to find a fix for something that can be totally out of your control.
If you remove all the internal walls, water, electronic and electrical devices, metallic pipes and conduits and wrap the whole building in a thick lead shield you will have a good chance of getting decent Wi-Fi from an ISP Hub.
Just a few things that can affect Wi-Fi in the average home …
Blockage (visible) …
Mirrors, furniture, fish tanks, people, radiators, walls, flooring / ceilings.
Interference (invisible) …
Cordless phones, baby monitors, microwave ovens, fridges & freezers, TVs, next doors Wi-Fi and Wi-Fi equipment, DAB transmitters, the list is endless.
My VM Hub 3 Wi-Fi went into meltdown when the local authority / police CCTV camera on the lamppost adjacent to my house was used.
Many people have accepted that the VM Wi-Fi is poor and have purchased third party equipment that is much, much more powerful than the VM supplied kit and once set up have wondered why they waited for so long.