You will have to find a reseller if you want to use Hafele as they supply to the trade like me and Mark.
Yes ebay have then when you know they are called Cam & Dowel, the KD is for “Knock Down”. Screwfix and all the DIY sheds, Ikea, etc that sell flatpack sell spares
Also watch what is given as the length, some are overall length others just use the protruding length excluding the thread