Consider critiquing your service providers and subs as to what they are doing and how. At the end of the winter season, we often send out questionnaires to customers asking for a critique of winter performance. When an unfavorable reply comes to the office, contractors will bend over backwards to ensure the customer concerns are addressed in a satisfactory manner. Why not do the same with your sub contractors? Give them feedback after the season, in writing, of what has bothered you (or your customers) about their performance.
Maybe the sub’s reporting or invoicing wasn’t up to par. How will they know if no one tells them of the issue? A written evaluation is not at all out of line. YOU are the subs’ customer. You might want to act like it. Too many times I get the distinct impression the contractor is afraid of the sub. You give them way too much credit. They need your money, just like you need your customers money.
Tell them what they are doing wrong. You might suggest corrective action. Don’t be afraid to tell them “line it is”. It is very unlikely they will go elsewhere – especially if you pay them in an appropriate time frame.
Remember – they work for you.