Refund Payment not received

My insurance hired a car of me in December 2015 and I returned on January 8. First car rental was supposed to refund me the deposit I had payed before I took the car. After weeks without reading receiving the payment I called in to enquire about that. It was then discovered that I gave them an invalid account number. It's invalid because I gave account number with 8 digits instead of 9, I'm banking with Standard Bank. First car rental the told me to communicate this matter with my bank. The bank then told me that they can't track the funds coming in from other banks and the account number I gave then doesn't exist so there's no way that funds would go through . First car rental is telling me that the funds did go through but it doesn't make sense how funds would go through to an invalid account. I have been sent back and forth between first car rental and my bank. First car rental now is telling me that there's nothing they can do its my fault because I gave them incorrect account number. But the argument now is that I gave them invalid account number, so it's impossible that the funds would go through. The bank confirmed that. The funds should still be in their banking systems.