My holding deposit disappeared into thin air and Avis expect me to sort it out myself.

I rented a vehicle from Avis for 60 days (December'21 & January'22) only because they have monthly packages. I normally use Europcar. The monthly rental works on a Month to month basis. I first rented a vehicle on 26/11/21, I went to Avis on 28/12/21 to renew for my second month. In the 1st week of January I was invoiced for December and 2 days later my holding deposit was released back into my account. No problems! I returned the vehicle on 25/01/22, invoice debited on 30/01/22 for January. Today is 11/02/22, I still did not receive my holding deposit. I spoke to Kholani on 3/2/22, Thuli on 7/2/22, Abraham on 9/2/22 (and forward him my email I send to FNB) and to Palesa at Mondeor branch (this morning), they all confirmed that FNB released my holding deposit on 5/01/22 (correct, but it was for my December rental). I specifically called Palesa at Mondeor branch to confirm the date she send the email to their Head office, to advise them that I've been invoiced, they can release the deposit. She confirmed she send the email on 01/02/22, I asked her so how can I be refunded on 5 January. All the consultants tells me to sort it out with my bank. Nobody seems to know what happened to my R12500 and cannot send me proof as I request. The tricky part is your deposit that you swipe does not reflect on your bank statement, fortunately my notifications comes through on email, so I could send all that emails to my bank and Avis, plus the merchant slip that I swiped. Your money can easily dissappear into thin air, how is it that a transaction is swiped but does not show a trace on your bank statement. I will never use Avis ever again. Geni