Increase my WiFi speed before I go elsewhere

I live in a standard small 3 bed house with plasterboard walls. I have a VM3 hub and get average 500mb into the house. tv keeps spooling and I am getting around 10% or less of the speed from the hub. My contract ends in April and debating between downgrading my speed so I pay less since I am not actually able to get the WiFi speed I would expect.

I do realise that there will be a difference between the hub speed and the speed into the Wi-Fi devices.

Try to get all 3 booster pods to hopefully improve the actual speed to my devices. Which I think it would be a miracle based on my decades of VM customer experience.

Or leave VM and go to BT/EE or another supplier.

I originally wanted to pay a bit more and get the 1gb speed to ensure that I got a good speed but that is unlikely to happen now.

I would also like VM to come and correctly fix the cable box to my outside wall after botching the initial box installation.

Any help to resolve this would be appreciated as would not to look elsewhere.