fitting FK coilovers

Hello all.

I'm new here but hoping to join the community.

I have a polo 9n3 and was hoping to fit the second hand fk coilovers I bought last weekend.

Upon going to fit I came across a problem in that the top mount didn't fit the spring.

Upon looking it's because I was missing the 'top hat'.

I'm under the impression it looks something like this:

As this would make the 2.75" internal diameter of the spring larger to suit the larger diameter of the top mount bearing.

Does anyone have any other suggestions or know what this part is called or where I can get something that will do the job from?

Thanks in advance :)