Wrong billing and turnarount time for refund

on the 18 July 2015 i rented a car from avis a class A vehicle for a day and returned the vehicle on the 19th July 2015 before 24 hr expired which was a sunday. i took the car to car wash and refuelling before return, which was on a sunday. when my invoice returned, i was billed for 2days everything and refuilling. i raised this concern with branch on the 23 when i receive invoice even today on the 28th July i haven't received my deposit back instead another amount of the same quantity due on invoice was debited om my account. i am not very sadi with the manner avis kathu conducts business..i tried on serveral occasions to conduct branch maneger tells me theres nothing ahe can do than wait for head office. this is not fair to me as a consuner cause its financially inconviniencing me... now i don't k ow how much they will debit from my account tomorrow