Avis-additional charges

I rented a car in December from Avis CT International Airport and having experience with previous rental companies, I made sure to include all the extra cover so of anything happened then I wouldn’t need to pay in. Upon giving the vehicle back, I was told the hubcaps are not genuine and I needed to write a damage report. All of a sudden I get an sms saying I need to pay in over R3000 for wheel damage. Firstly, it’s not wheel damage, they are hub caps and surely it would have been covered in all the extra cover? The hubcaps I returned the vehicle with are the same as the hubcaps I received the vehicle with. I don’t understand how they can be charging me in this way. One thing for sure, I’ll never use Avis again. I have only ever had positive experiences with Europcar, and I will definitely remain a loyal customer to them. Reference: ********** 00