I am receiving a notice just before I'm cut off that I have less than 10 minutes left in my Talk Booster Add-on. When I ignore the message I am cut off sometimes in mid sentence while on a call. I have $118 in my talk account with a base plan renewal scheduled for May 19. This just started...never had the problem before & I haven't changed my plan. What is talk booster add-on? & why am I being cut off?