Dollar Thrifty car rental refuses to release holding deposit after 9 days and counting

I rented a vehicle at Thrift car hire at Cape Town International airport. dates 25/12 2019 - 01/01/2020. Upon collection a R10000 security / holding deposit had been placed on my card. I returned the vehicle at the agreed date and time. It was received and accepted without incident. To date (09/01/2019) the security deport of R10 000 has not been released back to me. I have checked with my bank and they confirmed that this amount is pending on the vendours side. I have emailed Thrifty numerous times and the most i have received was "my request has been sent to the relevant department.