You can contribute and correct data in Google Maps by using the 'Send feedback' link at the bottom right hand side of the map. This will put you in direct contact with our community of data analysts who will review your edits. Corrections typically take up to 8-12 weeks to be reviewed, approved and rolled out into production.
If 'Send Feedback' is not available in your country or your correction is not implemented after using the above channels, please get in contact with the Support team by filing a support case in the Support Portal.