What are you getting for your money?
Most painting contractors use a contractors line of paint, is it the best ? No its usually a lower grade paint at a better cost line for the contractor like new homes are mostly painted with lower grade materials to cut costs. A quality repaint should never use these
paints. Really it comes down to prep work in case of exterior painting was the house power washed so the surfaces are clean before they start. Did they do a complete caulking to seal the exterior with a quality caulking .