To PM marketing team:
Suspect you will discover in due course but I doubt $5 saving will be enough to convert many customers to 90 day from 30 day. If that is truly the corporate goal suggest you get the saving up to $15. Especially true for folks on the biggests plans, perhaps somewhat less for those taking only text, or phone.
I just hope whatever the pricing structure PM settles upon it is adequate for the long haul, and not just the next year.