attaching Cupra seats to rails

Hi folks. I bought some Cupra seats for my ibiza without really knowing how to attach them. The previous owner drilled out the fasteners that go from the seat to the sliding bit on the rails

i'm trying to think if there is an easy solution to attach these to my rails. The fastener looks a bit like a rivet, passes through a hole in the seat and rail then is just the same on the other side.

It obvioulsy needs to be secure but still allow joint to pivot as the seat is adjusted. Does anyone know if there is an off the shelf solution to this?

If not i will possibly try a very short bolt with a smoothed section if i could ever find the right one!

Thanks for any help