Struggling to get hold of LIBERTY SHORT TERM INSURANCE to cancel my insurance with them

I've been trying to cancel my vehicle insurance with them for weeks now without any luck. Every time when I call I get to hold for more than 30 minutes with no luck. I've sent an email, they tried calling me once and sent me email saying they didn't reach me.

LIBERTY SHORT TERM INSURANCE is unreachable!!!!!!!!!!!!!!!!!!!!