Hi,
You could try the following options to control how it's pronounced and see if it works.
"Press 6 for Main Roads W. A." → adding periods often forces the engine to read each letter individually
"Press 6 for Main Roads W A" → keeping a clear space between letters may work depending on the voice
"Press 6 for Main Roads double-u ay" → spelling it out phonetically if needed
Hope this helps , happy to hear other ideas from the community.
------------------------------
Phaneendra
Technical Solutions Consultant