Has anyone found unexplained calls in their detailed call records?

Some background:

In the past, Vodafone used to attach a detailed outgoing call log to the bottom of their bills. At some point they stopped doing this and made the call records available via "My Vodafone". I've been downloading these every month for a while. If the bill was larger than expected, I'd scan the records to see why.  Recently, as part of learning Python, I wrote some code to parse the records.

I found one unexplained call record. The CSV is:

"Date & Time","Number","Usage type","MINs / data","Cost $"
"18 Mar 2019 03:11 AM","vodafone","Call (to Info, or other)","93:50","0.00"

At 3 in the morning, a 93 minute call was made to a vodafone service number. It's not voicemail, it would have had "Voicemail" in the called number field.

Now the mystery part: The phone concerned is an old Nokia feature phone, not a smartphone. At night it sits on a table connected to its charger, my wife doesn't want it near the bed in case it catches fire... so there is no way and no one (or cat) to accidentally operate it. The call didn't show up in the phone's call log.

I contacted Vodafone support but they had no explanation. The support person said she would pass the call to "back end technical support" and send a txt if they found anything. I'll update the thread if I hear anything. It was a zero charge call so it's not a big deal, I just wondered if anyone else had seen anything like it.