Last thing you should ever do is cancel a DD - it will initiate a cascade of problems for you.
Just call it in as a fault. Call it in on 150 (VM Phone) or 0345 454 1111 or (any other phone). Calling at 08.00 midweek -- is the best time - although people are still reporting getting through fine at other times with no long waits.
You can also text them on 07533 051809 include account name/number and what the issue is – replies may take a bit longer
A VM person should pick this up here and respond, but it can take several days - calling is the quickest option.
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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.