I closed my slingshot account about two or three years ago as I moved overseas.
It seems slingshot have now assigned my old italk number to a new customer. That person has set up their own voice-mail box BUT it seems the italk system has remembered my email address associated with that phone number.
Now every time that person gets a voice-mail message it gets emailed to me.
I'd think this is a fairly serious breach of that customers privacy.
I'm not living in NZ so I'm not in a position to call slingshot about it but if a Slingshot rep in these forums wants to PM me I'll give you the phone number in question so you can see if you can get it fixed up.