From Longman Business Dictionary
overchargeo·ver·charge /ˌəʊvəˈtʃɑːdʒˌoʊvərˈtʃɑːrdʒ/ verb [intransitiveI, transitiveT]COMMERCE to charge someone too much money for somethingDivorce lawyers often overcharge women clients.
overcharge (somebody) for somethingThe company overcharged the government for labor and materials.
—overcharging noun [uncountableU]fraud involving the overcharging of corporate clients
—overcharge /ˈoʊvətʃɑːdʒˈoʊvərtʃɑːrdʒ/ noun [countableC]Federal law doesn’t require lenders to reimburse consumers for any overcharges.