EUROPCAR-UNACCEPTABLE

I am a regular Europcar customer and have not experienced anything like this before. We rented a Hyundai Alcazar in Cape Town from 11-16 January. The car drove well and we had no incidents. We returned it to Cape Town airport on 16 January around 05h30. Europcar opens at 05h00. The car was checked TWICE- not once, twice and signed off as ok.. Later that morning, I received a phone call stating there was damage to the bumper and rear light- I reiterate no incidents. I contested this and on Friday 23rd, I receive an Invoice for R24,023.15 for damages. I again contest this . Today 26 January, I receive an email from Collections stating I owe them R24,023.15 and the damages are now rear bumper, rear tail light and front. They have my deposit of R17,543.55 which has not been returned and are asking for an additional R 6,479.60. This is absolutely unconscionable and highly irregular!