Ratter, I've been a first-aider for 35yrs+, you did, imo, do exactly the right thing by calling 999, especially as it was an elderly person involved, even if age was not a factor I would be very wary of 'picking' someone up under those circumstances.
As for complaining, I wouldn't this time. Make as detailed a record as possible (and as someone else said, try to keep emotion out of it) and keep it safe so you can use it if there's any repetition with this person.
I think that by complaining in your own time might be seen as going over your managers head and possibly cause problems for yourself in future.