VM have discontinued boosters and replaced them with WiFi "Pods" which is the VM entry into Wireless Mesh networking.. they are available for free to customers on the gig or ultimate oomph packages, otherwise they come with a £5 per month charge.
If you are eligible for a free one, you may as well get one and see how it works, if you have to pay for it, then you're probably better off putting the money towards your own wireless router/mesh system that better meets your needs.
The Pods are currently out of stock with other customers that use these forums being told that stock should be available at the end of this month/start of next.