Avis car rental deposit not refunded

Rented the car with them last month and up to this day 28 days later they have not refunded me. When I call to ask about my refund they keep saying it has been processed. They probably processing R8million instead of my R8000. They are a **** . They take the money for themselves & rob off customers. I’m going to expose them on all social media platforms for their bogus business