Hi Shirley,
We are also on the Wind network and what I have noticed sometimes is that if the Wind network is unavailable (for whatever reason and usually I don't know any better) then I am connected via some other provider. When that happens it can be much more expensive.
Also it will depend on whether you are calling landline numbers or mobile numbers and also which country!.
If you are calling another Italian Wind mobile number it shouldn't be terribly expensive but if you are calling a UK mobile it can be absolutely ridiculous.
I had a fiddle with the settings on my phone and set it not to assign a network automatically so that it always uses Wind rather than any other network for outgoing calls.
Having said that I think there has been recent legislative change that restricts the prohibitive cost of overseas mobile calls so things should be getting better (ie less expensive!)
If you are adventurous you can register your Wind sim card/mobile online and then view the individual cost of your calls (makes interesting reading).
You'll need a bit of Italian for this but it's great practice!
Here's the link:
http://155.libero.it/pls/portal30/w155.home
TTFN, see you soon, Lesley