Called Rogers and they found out there's something wrong with voice mail "provisioning" on my cell phone number. The rep wrote a ticket and said it should be fixed in the next couple of days. I got the reference number in case I need it. He had no idea about the strange message I'm getting when I log in to My Rogers, though, and told me to try a chat session.
EDIT: Just did a live chat, but the rep couldn't figure out why I'm getting the pop up message. Guess it will eventually disappear.
Update: No word from Rogers and VVM still not working. Called in again and was told to reset my network settings, then disable Wi-Fi to see if that would work. It changed nothing, so the rep said he will call my number and leave a voice mail to see if it shows up in VVM. That was half an hour ago and I still haven't received a phone call. Be aware, that if you reset your network settings and you connect to a router that's protected with a security key, it gets deleted when you reset network settings. You have to reenter your security key again and click on join before your Wi-Fi will connect.
I asked a friend to call me and I got a voice mail on VVM, so problem solved. The interface for listening to messages is completely different in iOS 7 from what I was used to in prior iOS releases. It took me a minute to figure out how to get to the screen where you can listen to the voice mail. It doesn't show when you first look at VVM. Apple has done a lot of this in iOS 7 and, to me, there are many things which are a lot less "user friendly". I really don't understand why Apple did this. They seem to be forgetting about the old "KISS" principle.
Unfortunately once a voicemail has been deleted, there is no way of recovering it. Sadly this is how voicemails work. You can try and see if there was a back up done right before the voicemail was removed ( back up of the phone) but I believe back ups do not back up voicemails.