Dogs, water in the tunnels, wire cages around the roots of your plants, thumping... So sorry. There is a thread on the Roses Forum on the subject. And here is more info UC Davis article on voles.

Here is a link that might be useful: Help! Something Eating My Roots Off My Roses!!!!!

Unbaited mouse traps in the runs (next to walls, edging,,,,)
will help keep the numbers in check.

I had a horrible problem several years ago. I tried everything, watering the holes, grub control because they love them and nothing worked. Then we got our dog. No voles - no squirrels. Life is good. Try it!
Pat