Avis please refund me the difference

My car insurance rented a car for me after my car was damaged after a road accident. I collected the rental car on 09 August 2023 at Polokwane international airport, the lady who assisted me made it clear to me that when I return the car, the petrol tank must be full. On 29 Sept 2023 I returned the car ( was supposed to be returned on 09 Oct 2023), the petrol tank was full. I ensured that Jabu, who inspected the car saw that the tank was full. Jabu told me that I will get an sms (within few hours) confirming that I returned the car. On Monday, 02 Oct I still didn't not receive the sms, I called Avis - spoke to Bahula who confirmed the car was returned, but i will not get R2500 that i deposited. R886.31 is deducted ( from what I was supposed to get back/ deposit) because the petrol tank was empty when I returned the car. I disputed that, and Bahula said he will lodge a dispute on my behalf, they will come back to me within 3 working days. On 03 Oct 2023, R1613.69 was deposited into my bank account. I have been waiting for Avis to share outcome of the dispute I lodged on 02 Oct with Bahula.