Using non PM Contractors

[Manco Snead]

Greetings,

Have an OOS duplex with a PM. Needs interior paint; PM says the contractor he uses is months out for painting. He'd mentioned I could try to find a different contractor/painter. I just called some other painters in that area and they said they can get it done within 2 weeks. How should I approach this with my PM to maintain a good relationship and why would he be so stuck on using his one contractor?