Same happened to me in dez 17’ in Perú… I initiated a chargeback process - no luck. Everything seemed fine, they couldn’t detect a problem, but there were 20% too much in the app compared to my receipt received at the restaurant. At the end someone from the support told me to log out from the app and reenter (of course I had to enter my number again, sms arrived, logged in). Then what a surprise: the amounts changed suddenly to the right ones in the app!