Impossible to get hold of and no response to any requests for contact

These people are impossible to get hold of. Been trying for a week to get someone to help me change my installation appointment. Sent emails, logged queries on their site, tried on the app, tried calling, even tried their Bot! Absolutely no response or assistance. Now they are going to show up to install next week and find that we are not moved into the property as yet! I'm so frustrated!