Cable needs burying

I need help in getting a cable buried.

VM have sent engineers out twice who have both advised that a specialist would be out later the same day as they can't bury the cable. 

Obviously these specialists have never been out and we are now 10days into a life without broadband.

How can I get this rectified?

The Webchat and telephone customer service team haven't been able to help and just keep sending regular engineers out.