Mine is also a 2017 Model S and I purchased the FSD software, and two months ago I went ahead with the Infotainment Upgrade which means I also got my HW3. They wil give you the HW3 if you have repurchased the FSD Software. Submit a service ticket from your app and let them know you want to either (1) Just get your free HW3 upgrade or (2) You want to purchase the $2500 Infotainment Upgrade and also get your HW3. They will triage your ticket, confirm if your VIN qualifies right now and get back to you. Not all VINs quality for it right now, but they will in the coming months.
Details about the Infotainment Upgrade =
Infotainment Upgrade