General advice on here is never cancel any existing BB contract until VM is installed and running to your satisfaction Having 2 running for a few weeks is a small price to pay for continuity.
Your contract and payments don't actually start until the day it is installed and activated - and thereafter you have 14 days "cooling off period" where you can just cancel it at no cost
However that may be different if you have no existing BB supply. Look at OpenReach, Sky, BT options and see if any of those could be installed quickly as a fall back.
That said, are you trying the Pre-installation and delivery team - they may have more info?
On.. 0800 052 1734
Call at 08.00 for the best chance of getting through quickly. There are many possibilities why this has happened so see what they say
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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.