Avis please help me sort out my issue

Avis always gives me such a splendid service, until now. I went to book at car at the OR Tambo Airport on 24 November 2024. I was informed that there was an amount of R5 376 that I owe. I then paid the amount instantly. After that I also paid the an amount of R7000 for a booking of Toyota starlet which I returned to Avis in Centurion . On 7 December, I went back to OR Tambo Airport to hire a car again. I was then informed that there is an amount of R5376 due. I told the lady who was helping me that I already paid that amount on 24 November 2024. After a long back and forth, they apologised and said they will fix the problem with the relevant unit. I then booked a VW Polo for R6500, changed it in Potchefstroom and was given a Suzuki Swift. I then finally returned the car at Centurion on 14 December 2024. A few days ago, I saw that my account had a positive amount of just around R11 000, which I assumed it was return of the deposits for the different cars I had booked. Then I used the money for some of my personal matters. Recently when I opened my account app and I saw that there is a minus amount of over R10 000. I am not confused and shocked. What is going. Please help me resolve this matter because I don't understand how one minute you have positive balance of over R11 000 and now I have negative balance of R10 000 which I don't have and this is frustrating and is causing me so much distress