Hertz bring back my money R18000 IMMEDIATELY!

Good day

I hired a car with Hertz Cape Town Airport on the 17th of Nov 2021. They deducted R18 000 as a holding deposit above the rental amount. I returned the car on the the 21st Nov 2021 in order. They checked the car and everything was ok. It’s been 25 days now and the R18 000 is not in my bank account. I called the call centre and there’s no response and I have sent emails no one has responded.