AVIS and our credit card ! Watch out !

We booked a car with AVIS, CAPE TOWN airport from the 22nd of May to the 7th of June 2018 and took an extra insurance. . Last year, we have been thrilled by the service. When we gave back the car on the 22/06 ,we knew and agreed there was a scratch . On the 15th, 7000 rands has been taken from my husband's credit without any warning, justification. Hello! He sent an email,asking very politely, to have some explanation. AVIS rep**** they got his email. We haven't heard of them since. Hello ! 7000 rands, price of plane ticket to fly to Europe! Hello ! The lack of respect for the client is dreadful. I am pretty sure it is a mistake and still trust AVIS but ...