Slow to return deposit

Six days after I returned the vehicle, I phoned customer services to enquire why I hadn't received the invoice yet. I was told politely by Emma that she would enquire and phone me back. She did so and confirmed that the account had not been reconciled yet by the finance dept and that I would get the invoice the next day. I did receive it the next day but how long would it have taken if I hadn't phoned them to tell them their job? 8 days later and the nearly R10,000 deposit is still not in my account. This is unacceptable.