I am part-owner of a large swedish webshop company, and we happen to use Klarna. Klarna is simple and will probably work for most companies.

While it's unusual that there are cases of fraud, it does happen. Every time it has happened, it's enough for the victim to do a police report and just tell Klarna that they have been victims of fraud, and Klarna will remove the invoice due to their fraud policy. Obviously, the police report is meaningless as the police does nothing.

I wish there was a better alternative to Klarna, but sadly, I know of none.