1) Look at terms of service of the site to see if you can flag it and get it removed.
2) Create social media profiles to push down the negative result in SERPs. Make sure to link to each other and to your website.
3) Create profiles on popular review sites in your country. Get happy customers to review you on those sites (target happy customers and not ask for positive reviews). Link to your social media pages and your site.
4) Create a Wikipedia page, if possible, to rank for your company name.
5) Do some link building with influencers (such as bloggers that would be interested in your company). Get them to review your product/service. Make sure they're worth your time, SEO-wise.
6) Check what keywords that negative result is ranking for and create a company page using those keywords. For example, if ranking for "complaint", create a page called "[company] complaint and review form".
Those are the ones off the top of my head.
2) Create social media profiles to push down the negative result in SERPs. Make sure to link to each other and to your website.
3) Create profiles on popular review sites in your country. Get happy customers to review you on those sites (target happy customers and not ask for positive reviews). Link to your social media pages and your site.
4) Create a Wikipedia page, if possible, to rank for your company name.
5) Do some link building with influencers (such as bloggers that would be interested in your company). Get them to review your product/service. Make sure they're worth your time, SEO-wise.
6) Check what keywords that negative result is ranking for and create a company page using those keywords. For example, if ranking for "complaint", create a page called "[company] complaint and review form".
Those are the ones off the top of my head.