Unbilled usage screen doesn't show call details correctly

[djmagnifique]

My wife recently had to call her car insurance (0844 number) as someone went into the back of her car. The call seemed quite long so a couple of days later I checked on my unbilled usage through my virgin media and was surprised to see that the call was 14.45 minutes and had a pre vat charge of £6.61. I sent an email off to virgin about this and they advised me that the call was actually 75 minutes long but gave no explanation as to why it didn't show this and only said 'I sincerely apologise that I can't go into further details regarding this call as it's not been printed on a bill.'

Is it normal for calls over an hour long to not show correctly in unbilled usage or is this a glitch that needs fixing?