The global online ad racket; Ed Butler investigates how criminals are ripping off advertising firms to the tune of billions every year.

Andrew Lissimore the CEO of a Canadian company that sells high-end headphones tells us what happened when he hired an ad-tech firm to organise targeted advertising for his website.

Ad fraud expert, Augustine Fou explains that the problems with digital advertising really began about a decade ago, when advertisers stopped selling their ads directly to publishing websites and used ad exchanges instead. We also hear from a former hacker who now advises companies on how to keep hackers and fraudsters at bay.

Presenter / producer: Ed Butler Image: Online business marketing; Credit: Getty