You can see the original fact sheet of the investigation here (http://europa.eu/rapid/press-release_MEMO-15-4782_en.htm). The reasoning for the investigation is at the bottom. There were two complaints and an independent investigation by the committee.

The fines "reflect the gravity and duration of the infringement. They are calculated under the framework of a set of Guidelines last revised in 2006." (http://ec.europa.eu/competition/antitrust/procedures_101_en....). There's a link to the guidelines on the page.

I also had a look at how to file an anti-trust complaint but to be honest, most info was over my head and more appropriate for a lawyer - this seems to be a good start: http://ec.europa.eu/competition/contacts/electronic_document...