Have all of the people with problems reported them to VM? That's the only way that a "wider" fault can be identified.
As well as the “check service,” weblink there is also a Service Status number 0800 561 0061 which usually tells you of local issues, down to postcode level (that might even not yet be listed on the Service Status web page) that may give you more info.
Finally, set up a free “BQM” to continually monitor the state of your connection and record any dropouts. It does it 24/7/365 and it keeps a visual record of all your network disconnections, useful data to have in discussions with VM.
https://www.thinkbroadband.com/broadband/monitoring/quality
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John
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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.