Charges not explained !!!

I rented a vehicle for 12 days, right after i returned i received the invoice with a 0 amount due During the rental i had 2 extensions done in which the amounts were informed to me. While awaiting my deposit to be returned, i had further charges on my account and not one person in customer relations can explain what they are for. The invoice is not user reading friendly and the company does not communicate whatsoever regarding deposits or amounts charged .

Frustrating !!!