This article will explain what the User Permission - Modify Payment Method Surcharge is for 

User Permission > Special Actions > Modify Payment Method Surcharge

If your Dealership has a Payment Method Surcharge automatically setup, we have given a way for certain users to have the permission to be able to modify / override the automatic charge

This user permission must be enabled for those users that you want to have this action 

For further information on Payment Payment Surcharge, please review this article - Payment Method Surcharge - Setup and How to Process