Open the trip in the app and choose Report a problem or dispute a fare, pick what went wrong, and you get an answer on the spot. On WhatsApp, write to +592 655-7775 and say what happened; if you took more than one ride this week, we ask which one. If you were charged more than the price you were shown, you get the difference back automatically.
Anything we cannot settle on the spot goes to a person on our team, who replies within 2 hours. You can raise a problem up to 30 days after the ride; answers are immediate for the last 7 days.
See also How do refunds and ride credit work?.