Just be aware that new boosters are now currently only supplied free if you have the Hub4. if so they are worth trying. If not, they will charge £3/month rental and they aren't good value at that. The maths says that you would be far better putting those monies towards sourcing your own better wireless equipment (which is yours forever) with the Hub in modem mode to solve your wifi issues.
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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. On VIVID200, Talk Anytime Phone, x2 Mobile SIM only iPhones.