How to update the plugin?
In the OpenCart admin panel, navigate to Extensions > Installer and uninstall the old package (by doing this the Montonio payment methods settings will be deleted, you will have to re-configure Montonio payment methods again after the update).
Click the “Upload” button and select the new “montonio.ocmod” package (the extension will be installed automatically).
Then you will need to configure payment methods. Check the guide here: Montonio for OpenCart
If you have additional questions and need our help, feel free to contact our support team via the chat in the bottom right corner.