My experience is that I get ignored when I try to raise and issue. You can see them answering other people but not me.
A few years back I was on the point of clicking on a link of a suspicious email because VM ignored me and would not confirm if it was fake or not. The email threatened me with disconnection for non payment of a bill. I had recently changed my direct debit details so couldnot ignorie it, in case something had gone wrong.
I kept Tweeting through the day, only to be met by silence, whilst VM answered everyone else within minutes. I ended up at a VM shop, when they had one, with paperwork relating to my bank accounts.