Borussia Dortmund's new scheme does not mean a ban on supporters using their phones and system is voluntary for fans. Filming and using social media in stadiums is becoming a problem for fans. Borussia Dortmund has an unusual solution to. Borussia Dortmund take aim at influencers in bid to protect ‘stadium experience’ - Dortmund said a survey of 1,000 match-going fans had revealed annoyance at ‘selfies’ and the use of ‘social media’.