Billing mistake


I started years ago on the Visible plan, then changed to Visible+ about 5 weeks ago when I travelled to Puerto Rico.  When I returned after a week, I changed back to the standard Visible Plan.  I was appropriately billed $35 for last month, but now I'm still being billed that amount, even though I know I changed plans back to the standard plan.  When I login to my account, it shows that I'm on the standard plan and should be billed $25.  

Connai is not helpful, so I don't know where else to go to get resolution on this matter.  Any ideas?  I have screenshots to support all this, but this chat isn't letting me upload them.  Thx!