Up 1GB from the previous offers, Virgin Mobile are offering a 3GB bonus ontop of their (new normal) $50 15GB SIM only 12-month plan, with the usual 10% Velocity discount making it $45/mth 18GB.
Like previous offers it doesn't show up if you try and upgrade as an existing customer. I haven't tried asking on the phone or online chat if they can apply it manually (as like the last offer I don't think I'll switch personally) but I would be pretty confident you could squeeze it from one of the reps surely.
I picked up the 17gig deal a few weeks ago and have been very happy with the service and coverage.
Plus, having free Spotify and iHeart radio leaves plenty of data left, without having to worry.