Hi Mtore,
welcome ro the Apple (user-to-users) Community!
Re: "Siri on Iphone 15 is abbreviating directions (eg West to W.)
I live on a street with a name such as East Street and so it comes out always as E. Street"
There are a few different ways to go about dictating your correct address :
Perhaps one of the three suggestions below may work best for you.
✽ Seems the more you use Siri, the more Siri knows and responds with what you need:
You could try telling Siri about your address, to see if that helps have it entered correctly:
Tell Siri about yourself on iPhone - Apple Support
________________
✽ Beginning in iOS 18: There are now Commands for dictating text on iPhone - Apple Support
Eg: says:
"When you dictate text, you can say commands for punctuation, formatting, capitalization, and more"
So in iOS 18: you can say: "Change … to … (ie: Replace existing text with new text)
___________________________________________
✽ For much more control in dictating and editing text, you could try turning on and using "Voice Control":
Eg: An online Video shows: How to use dictation and edit text with Voice Control on your iPhone — Apple Support
https://www.youtube.com/watch?v=k-ykg3jZ9_k
All the best :-)