Not returning deposit

I hired a vehicle from OR Tambo and returned the vehicle on 16 June. As of today, 27 June I have still not received my deposit of R3500. I’ve never experience this lengthy delay with any car hire company before. Initially they told me I’ll have my deposit returned within 7 days. I’ve tried follow up op by calling the call centre and nobody answers after holding for a length period, they don’t reply to emails, they don’t reply to WhatsApp. Pathetic service. I don’t live in South Africa, each time I call I hold and pay a lot for an international call that doesn’t get answered.