These stories happen all the time. There is probably at last one such case for every service provider ever. One customer can have all the bad luck, so one story doesn't make or break a product, but I found this saga by a VOIP.COM user almost moving: I Give Up!
One of the striking things I saw in there is this:
when the techs do talk and they tell you we really don't guarantee you phone service - you should only use a regular land line for any communications because VOIP.COM is not to be considered reliable (actually had one person tell me that)
If that's true, it's pretty incredible. What does it say about the state of VoIP?