Visual Voicemail No Longer Will Delete Multiple Items . . . .

After getting tired of having to delete countless voicemails from spam callers, I installed Visual Voicemail so I could delete all at once. That worked for weeks, but now no longer will work that way. For example, there were six voicemails I wanted to delete today. I clicked the three buttons on the top right, chose delete, chose all, hit the delete trash can on the bottom, and got a message "Refresh Failed". This has been going on all week. Thus, I have to delete one at a time. Does anyone know why that is happening and if that can be fixed?