VM never stated it was shared bandwidth either in any small print or t&C's.
Wish people would search forums, but basically, you shouldn't have to pay similar to other customers that have superior kit to what you have. The hub5 is WiFi ax and has a 2.5gbps port that is useful in modem mode to connect to a 2.5gbps or above switch.
Raise a formal complaint, or if near end of contract, use as a reason for not renewing. You can get a hub5 as long as stock levels allow, you just have to stand your ground. You should not have to pay for inferior kit compared to another customer on the same tier. If you don't intend to make use of hub5 as a router and the WiFi ax capability with ax capable devices, OR you don't intend to use in modem mode and connect the 2.5gbps port to a switch that has 2.5gbps or above, then a hub4 is good enough.