Budget rent a car bad service

I rented a car in the 30th December 2019 to 2nd Janiary 2020. Budget room R2500 deposit and when I delivered the car said I will get an invoice and my money will be refunded. I called Friday 3rd was told invoice not yet in I must check Monday. Over the weekend I got the invoice then Monday the 6th I called and could not go through and 7th January 2020 I called and lady said my money will be released and if not I must call back. I called now and the lady puts me on hold for more than 10 minutes until I terminated call because of airtime. Why must I struggle to get my refund since I returned my call in time.