Switch to 90 day 3gb at 4g speed subscription

[So123]

I'm wanting to change my subscription to the 90 day 3GB at 4G speed plan but am unable to. Is it possible to such to this plan? 

[softech]

@So123 

not all plan has 90 days option.  At this time, only the new activation only plan $21 has a 90 days option.  All currently available plans for existing customers do not have 90 days option