Aluminium and Glass contracter not to be trusted

Contractor was appointed 14th July 2015 to replace windows and aluminium doors for small shopping centre. In terms of his agreement to attain a 20% discount he was paid in full on the 16th July 2015. Work commenced on the 4-day project on the 17th July 2015.<br> <br> 6 weeks later, he has not completed the contracted works. He does not answer his telephone. When he does accidently answer, he promises to give feed-back within an hour and never phones back.