All BB suppliers cannot and do not "guarantee" wifi connections for obvious reasons based on physics.
They all will make efforts though to "boost" the signal from their Hubs.
VM now supply “wifi pods” (no longer “boosters”). These are free to customers on the 1GB or Ultimate Oomph packages, and so are worth trying if you are on one of those.
Otherwise, you will be charged £5/month - which does in fact compare favourably with BT's monthly charge for "whole home wifi" of £10/month
However, at that level of investment you would soon pay off those costs by buying a "better" wireless solution that will be yours to own and use forever.
But your call of course
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John
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I do not work for VM. My services: HD TV on VIP (+ Sky Sports & Movies & BT sport), x3 V6 boxes (1 wired 2 WiFi,) SH2 in modem mode with Airport Extreme Router +2 Airport Express's. On VIVID200, Talk Anytime Phone, x2 Mobile SIM only iPhones.