one guy has sent me an email that they can take me to court this is the site complaintsboard.com.au ppl commenting on the complaints, one complaint got more than 40 comments and it has come on google now,, and that company commenting too.. i m afraid i will be in trouble with this web site.. i have written terms and conditions
Even if you have terms and conditions, it still depends on the country where you're from if they are valid and if you can still get sued for slander/.. or not. You should investigate these things before you start a website like this because you know in advance it could lead to troubles ?!
If the companies are complaining it means your site has credibility and traffic. To be fair you should let companies post their reply prominently and contact the person who posted the complaint through your website, just protect the email and identity. This will allow the parties to settle the complaint amicably and modify the complaint statement to reflect any settlement. If your complainers get results then everyone wins and you will get much more traffic.
For me this site is really good and their are other sites in Aus which get input from other people about service providers. You should ask this here i guess whirlpool.net.au/ because i always use this for these sort of questions, which are related to Australia Though I like cerno's comments it would help you... Try to make some mechanism where company can act and identities are hidden.