The 2nd install guy arrived today. Some improvements. However his silicone sealant gun broke recently, so he was unable to do anything with the hole. He suggested I could get a builder to do it.
I suggested Virgin will have to come again and fix it. A manager is ringing me back within a week to send someone out. I have given up after 90mins on the phone to them today. I signed up at £35 a month but the contract now says £39.99. They have agreed to change it.