[joeysteele]

Many times, In the main for an ambulance.
I did for my Grandmother when she collapsed while I was out with her.

Also for ambulances for a good friend who was severely brain damaged in a car accident years ago, he often had seizures that required urgent hospital attention so 999 was the way to get him there as near immediately as possible.
We lost him though a couple of months back.

Have also called 999 for the Police and fire service too for others.