Six things that forced my hand in quitting VM forever were:
1. Weekly extended periods of downtime - and the lies told by their CS that everything is OK. I am now with TalkTalk of all people and other than the 5 mins of downtime when OR switched my line to "Fibre", been solid.
2. The very frequent and rather sharp price increases. With TalkTalk, my bill since joining has come down (re-contracting worked for me in this instance)
3. The marketing lies and childish slogans "the magic in our cables". "Fibre Optic" but copper coming into the home. "Widely available", but about 44% coverage
etc. Had more ads banned than anyone else. They have been peddling lies about their service ever since they laid the cables and will never stop.
4. Embarrassing upstream speeds that are throttled if you use it "too much". Tell me how can it be "too much" on an unlimited service? Again, the usual lies.
5. Every router/modem they ever sent apart from the Motorola Surfboard had been problematic, either the firmware in the device itself or the way it interacts with their BSRs.
6. The pings and jitter were horrendous. Useless for gaming.
Your first experience of them should sound a loud warning alarm to you about what to expect from them. VM used to put all their best staff on sales - and India on aftercare. Says it all if even their sales are now useless. They've slashed and hacked at their customer service for years and you've experienced the result. Best to just avoid them to be honest unless you really are having serious issues over BT's OR network and there's no alternative.