According to figures from the Financial Ombudsman Service (FOS) Revolut received 171 claims from UK customers between January 1, 2015 and December 31, 2018; Monzo received 82, Starling Bank received 51 and Tandem Bank received 30; a Revolut spokesperson tells the FT, “While our current rate of complaints is very low proportionate to our customer base, we are fully committed to continually improving our services and will always do all we can to ensure our customers have no reason to complain.”; when comparing these figures to bank complaints it shows that fintech firms are well ahead of incumbents. Source.