Tell my contractor to stop lying!

This one contractor is making my blood boiling! They made me come down for meeting when I'm busy designing my house and the boss was late for 15 minutes and the assistant was sitting there smiling for my goodness sake don't know what.

The project manger demanded their work progress and they have only done 3% of the work in the past 3 months! If it isn't for this meeting, they would have continued to slack till their contract expires!

Then they still have the face to ask me to sign the material sample forms when there is no setting up on site and moreover they don't even bother to find and fill in the correct forms. They asked me to choose the colour for the roofing material but they can't even answer me what is the colour of the linkway roof on site. The assistant said they are red clay roof tiles but when I went to site secretly half an hour later, it is WTF blue aluminium sheeting!

Lucky I am only a consultant, not the project manager.