Don't want to sound harsh or anything but when ever there are legal matters it always sounds harsh LoL but anyway this is what I know .
From my knowledge,
If the private seller that you purchased the car from is not involved in any business of selling and buying cars his not considered a "Supplier" as per the CPA , then the Voetstoets clause "as is " does apply . The CPA did not abolish that clause , To my knowledge it only really apply to business .
Especially if you had taken the car for the check up and in yours and the sellers mind , there was nothing wrong with it . Unless you can prove that he deliberately hid the defects . Then maybe you have a case , but in all honesty , you will spend more money in the courts with this then just fixing the problems .
Westbank wont help you , they are just the finance house , you needed money to buy the car , you borrowed from them .
As with the above , you will have to prove that Bosh were negligent in their checkup , but then as well , what are you going to get out from them ? They wont buy the car from you and reimburse you , you didn't buy it from them. Whats their terms and conditions say? If you wanted a full proper check on the car maybe BMW would have been a better option?
You should go back to the seller and speak to them . But if he says that he does not have any prior knowledge of the problems before he sold the car to you, and you can not prove that he did have knowledge of the problem before he sold it to you , then im afraid there is nothing you can do about it .
Its the buyers responsibility to prove that the seller had knowledge of the damage/ problems before selling the product and that he sold it without telling you about these problems with an attempt to defraud you . It can be difficult to prove this.
Did you and the seller write up a contract ? Was the Voet-stoets clause in there?