update

just took all centre caps off the car and, one at a time, placed them face up on a hard surface, and by hand started pushing down around the edge of the cap, to work them back into thier original shape.

after a couple of minutes on each one they now look and fit much, much better. ok so not perfect but nearly there.

how long they will stay like this i dont know, but at £15 each its worth a try....