Unable to select my free perk via Self Serve

A few weeks ago, I upgraded to a new phone, and had to change my plan along with the upgrade. On my previous plan, I had Rollover Data selected as my perk. I would like to do the same for my current plan. However on the new plan, I’m unable to select my perk, and am always met with the “Unable to select a perk right now” message in self serve. 

I’ve tried on various devices and browsers, but always get the same result. 

Any help with this is greatly appreciated.