I live in CANADA/Ontario and I have a telephone connection on my name from one
of the leading service providers. But in the telephone directory
listing my name was spelled wrongly. My name on account is correct. On
my monthly bill I will get correct spelling. Mistake is there only on
directory listing (online and printed book)

I was reading in some forums that I can file a law suit againest the
service probider, as I lost my business because of their mistake.
whome should I contact to flie the law-suit and what is the success
rate in CANADA/Ontario?

I think there is a note in the phone directory saying that they aren't
responsible for errors.

That ebing said; just because they disclaim it does not mean they are not liable.

For instance, if I say that if you come within 50 feet of me, i'll
punch you in the face and I cannot be held responsible.  Then you come
within 50 feet and I run over and punch you, that does not mean I am
not liable.