I had a dispute with Diamond Trade (diamondsplatform.com) and went to their complaints process. They have an internal team that just defends the company. Then they said I could go to an ombudsman - but the ombudsman they use is industry-funded and rarely rules for the client. The system is rigged.
Pros: Personal attention|Regular platform improvements|Social trading features|Market news feed
Cons: Desktop app not available on Linux