Rental deposit never returned, instead more money taken from me with no explanation!

I rented a car from the 6th of April until the 12th of April with two extensions in-between. Every time I extended my rental the rental agent informed me that they take a little more money off my account every time I extend and all this will be refunded to me upon receiving my deposit back. I returned the car on the 12th of April and returned home to Mos***. It is now the 25th of April and I have still not received my deposit back, instead, Budget went ahead and deducted a further R4000.00 from my account. I have emailed their customer service twice and have only gotten an automated response that they will get back to me. I still haven't received anything and can't help but feel as though I've been ****** of my money by this rental service.