Without consent

Service from Avis has been unprofessional . I've been using a rental vehicle for 4 weeks through my insurance company and the vehicle has been extended every week without fail. Avis then called me to find out if the rental vehicle was returned. When I advised no it was extended they placed a hold of R3262 on my credit card without approval or discussion. Now a week later I'm still battling to get the hold of my credit card. How can they just use my credit card without my consent.