Putting spare wheel in correct location on rear door.

[OuterMongolia]

I have a MK 5 smiley face ,high roofed transit camper van . when I brought it the spare wheel was [and still is] bungeed in place behind the single passenger seat .This takes up a lot of space and isn`t very secure .. When I driving away after buying I started to see other models . I noticed their spare wheel was on the rear door!.On looking at mine I notice there is still an attachment for the wheel on my rear door .How is the spare wheel secured on the door? I have just a curved lug where the spare wheel should be. Presumably there must be an attachment that secures the spare wheel onto this location? Are they easy to get hold of ? thanks Sam .