wheel nuts; floor mat clips

Good morning everyone,

Does anyone know of a site where I might be able to pick up one of those two part plastic clips which are used for securing the floormats to the studs on the floor? A valet service managed to vacuum one up a couple of months back...

Also, one - just one - of my wheel nuts has corroded on the offside front wheel. Again, is it possible to pick up such a trivial item as a one-off somewhere?

The car is a Jan 2004 SLK 230, and I am based in the UK near London

Thanks for any help,

David