Log in to your Pokémon Trainer Central account and find the tournament that you participated in. Report the issue to the Tournament Organizer for the event. If the issue is related to your record during the tournament, the Tournament Organizer will then contact Play! Pokémon to have the record corrected for that match.
If the Tournament Organizer does not respond to you within three days, contact customer support with the subject “Match Record Appeal” and the Play! Pokémon team will do what it can to assist you. Please note that without confirmation from the Tournament Organizer, Play! Pokémon may be unable to make any changes to a match record.