I wasted quite a lot of time reporting these ads to ebay each time - at least the Vauxhall ones - but the fraudulent ads would at least then quickly disappear.
But the 'report item' function on the ads no longer works because ebay seem to have changed their settings to disallow reports of fraudulent ads if the ad doesn't have a 'valid item number'.
So it seems that having been inundated with reports of fraudulent ads, ebay have responded by disallowing reporting. What a brilliant response by ebay.