Just as a quick suggestion, I thought I'd send the non-medically minded here for some advice on when it IS a good idea to call an ambulance.
After you've had a good read, allow me to give you a few ideas of when not to. These are calls that I have personally been sent to, so are not made up...
Please don't call if 1) you have a paper cut. 2) you have been prescribed antibiotics for an ear infection, and 10 minutes after taking the first tablet your ear still hurts. 3) your mobile phone battery has nearly run out and your charger is not working. 4) you are a GP whose surgery is about to close and you don't know what else to do with your regular patient who's back again complaining of a sore throat.
There are many many more that I could think of, and if you're an ambulance person reading this, feel free to add some of your own. A prize of kudos goes to the most bizarre reason for a call out.