The only way to really get rid of them is trap them or use poison. Don't bother throwing any kind of repellent down their hole; they'll just dig a new hole.

Are you sure they're not moles? ...
Voles are tiny

Stoats and rabbits tunnel too ......
I live and let live, cans on canes do deter hem but you have to be persistent

You may just have to wait for the population to drop naturally, which it undoubtedly will - there are certain rules which must be complied with regarding poison and trapping, more info in the link below

https://www.rhs.org.uk/advice/profile?pid=792

Nope, not according to the link I posted, Snoop - but there are regulations about how you deal with them.

You may have Moles. Voles just dig holes, moles do the tunneling action. Check with RHS for proper eradication in your country.