As the title says, I have horrible phone anxiety. Just thinking about having to make a call makes it feel like my skull has suddenly gotten 5 sizes smaller for my brain, and my eyes are about to pop out. I've told my partner how much I hate making calls. They seemed to have listened or at least tried to be sympathetic. 

However, there are times when they'd still ask me to make a call for one reason or another (mundane things, like making a reservation or hiring help) and when I say no, get visibly frustrated. It makes me feel guilty and about as small as a pebble.

Most of the time said partner is understanding of my anxiety about certain things. But the thing that I dread the most, is the one they seem to not take seriously. How do I communicate that this is actually a really serious thing?