Can i use an adapter like chademo so can buy it once and use for all the cars as and wheb? Or would i need to get each car retrofitted?
CCS adapter has two parts; external adapter that makes the connector match, and an internal controller that is installed under the rear seat. So yeah, you need each car retrofitted separately.
But the price really is 299eur including installation, and can be done by a ranger.. So it's quite a bargain in my opinion.
2019+ Model S has the controller already installed, so they only need the external adapter. But your cars were older..