Drywall and door installation

I was referred to Jaco to asssit me with drywall and to fit a door. His response was quick when I called him. He came over for measurements and a quotation. I accepted his quote and paid 80% deposit. He sent Dirk to do the work who came a few times. And each time he came he brought a different person. Each person made a mess. As we speak the drywall is not complete and the standard is of poor quality. the door was installed upside down. The side to fit in a door handle is mounted to frame....The work is just below standard.