Visual Voicemail not deleting voicemails and Crashing the Phone App

So, my issues started when a spam caller from another country would call me 6+ times a day and leave 10 second voicemails of just static. I proceeded to block the number, then realized that even a blocked number can leave a voicemail. Without realizing, within a few weeks my voicemail-box was full.

When I delete the voicemails, they move into the "recently deleted" folder. Now, when I enter the folder and select "Clear All", they all disappear. BUT! When I close and reopen the app, there they are again! Even with a few voicemails still sitting in the regular voicemail box. If I try again to delete them, they disappear again. Then when I force close and reopen the phone app, I am faced with a plain white screen, and I am unable to select anything within the phone app (no favorites, no contacts, no keypad, nothing)

The only way to remedy this is to restart my phone entirely. When I do that, there all the voicemails sit in my mailbox!

I have already tried deleting each one manually (theres over 20 voicemails from this spam caller). I've called the voicemail by pressing "1" on my keypad and deleted them the old fashion way. I've reset my Network Settings. No matter what, those **** voicemails still sit in my mailbox, either in the regular mailbox or in the "Recently Deleted" mailbox.

I will say that since calling my voicemail through pressing "1", the automated message says I have no voicemails, but the actual Visual Voicemail on my phone doesn't actually delete anything. And if I try to delete or "clear all" more than once, the whole app freezes with the white screen

Please help. Is this an Apple issue or a phone service provider issue?