Voicemail misbehaving while roaming

[hallmr09]

I'm in Canada for the week, and I had a voicemail on my phone when I got here. Today my phone has been vibrating every 5 minutes telling me that I have a new voicemail, and it has even sent me several text messages saying "@@0 new vmail 0 urg 0 fax *86" even after I deleted the voicemail. I have tried turning vibration off for the notification, but it still vibrates. I have also tried deleting the data and clearing the cache in the Phone app. This is driving me up a wall.

How can I fix it??