Does the offer appear as the giant banner at the top of the itinerary in My Trips detail page? I have a different offer for upgrading to F, so I wonder if you only get one offer at a time.... (see attached screenshot)
Try this:
- Click 'Learn More' (for your F offer).
- Go Back via the browser button.
- Refresh.
Mine just switched from $50 UC + WiFi to the $5 WiFi offer. YMMV.